import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.stream.Collectors;

public class Main {
    private static FastScanner input;
    private static PrintWriter output;

    public static void main(String[] args) throws IOException {
//        openFile();
        openConsole();
        int n = readInt();
        int start = readInt();
        int end = readInt();
        boolean isFound = false;
        for (int i = start; i <= end; i++) {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        }
        if (!isFound) {
            output.println("NG");
        }
        closeReader();
    }


    private static void solveC() throws IOException {
        int numTest = readInt();
        for (int i = 0; i < numTest; i++) {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        }
    }

    private static String readString() throws IOException {
        return input.nextLine();
    }

    private static int readInt() throws IOException {
        return input.nextInt();
    }

    private static void swap(int[] data, int i, int j) {
        int temp = data[i];
        data[i] = data[j];
        data[j] = temp;
    }

    private static void openConsole() {
        input = new FastScanner(System.in);
        output = new PrintWriter(System.out);
    }

    private static void openFile() throws FileNotFoundException {
        ClassLoader classLoader = Main.class.getClassLoader();
        File myFile = new File(classLoader.getResource("input.txt").getFile());
        input = new FastScanner(new FileInputStream(myFile));
        output = new PrintWriter(System.out);
    }

    private static void closeReader() {
        output.flush();
        output.close();
    }

    static class Pair {
        int id, count;

        Pair(Integer id, Integer count) {
            this.id = id;
            this.count = count;
        }
    }

    static class FastScanner {
        StringTokenizer st;
        BufferedReader br;

        FastScanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        private String next() throws IOException {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        }

        boolean hasNext() throws IOException {
            return br.ready() || (st != null && st.hasMoreTokens());
        }

        int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        String nextLine() throws IOException {
            return br.readLine();
        }

        boolean hasNextLine() throws IOException {
            return br.ready();
        }
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.File; File java.io import java.io.FileInputStream; FileInputStream java.io import java.io.FileNotFoundException; FileNotFoundException java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.PrintWriter; PrintWriter java.io import java.util.Arrays; Arrays java.util import java.util.HashSet; HashSet java.util import java.util.Set; Set java.util import java.util.StringTokenizer; StringTokenizer java.util import java.util.stream.Collectors; Collectors java.util.stream public class Main {
    private static FastScanner input;
    private static PrintWriter output;

    public static void main(String[] args) throws IOException {
//        openFile();
        openConsole();
        int n = readInt();
        int start = readInt();
        int end = readInt();
        boolean isFound = false;
        for (int i = start; i <= end; i++) {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        }
        if (!isFound) {
            output.println("NG");
        }
        closeReader();
    }


    private static void solveC() throws IOException {
        int numTest = readInt();
        for (int i = 0; i < numTest; i++) {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        }
    }

    private static String readString() throws IOException {
        return input.nextLine();
    }

    private static int readInt() throws IOException {
        return input.nextInt();
    }

    private static void swap(int[] data, int i, int j) {
        int temp = data[i];
        data[i] = data[j];
        data[j] = temp;
    }

    private static void openConsole() {
        input = new FastScanner(System.in);
        output = new PrintWriter(System.out);
    }

    private static void openFile() throws FileNotFoundException {
        ClassLoader classLoader = Main.class.getClassLoader();
        File myFile = new File(classLoader.getResource("input.txt").getFile());
        input = new FastScanner(new FileInputStream(myFile));
        output = new PrintWriter(System.out);
    }

    private static void closeReader() {
        output.flush();
        output.close();
    }

    static class Pair {
        int id, count;

        Pair(Integer id, Integer count) {
            this.id = id;
            this.count = count;
        }
    }

    static class FastScanner {
        StringTokenizer st;
        BufferedReader br;

        FastScanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        private String next() throws IOException {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        }

        boolean hasNext() throws IOException {
            return br.ready() || (st != null && st.hasMoreTokens());
        }

        int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        String nextLine() throws IOException {
            return br.readLine();
        }

        boolean hasNextLine() throws IOException {
            return br.ready();
        }
    }
} Main private static FastScanner input; input private static PrintWriter output; output public static void main(String[] args) throws IOException {
//        openFile();
        openConsole();
        int n = readInt();
        int start = readInt();
        int end = readInt();
        boolean isFound = false;
        for (int i = start; i <= end; i++) {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        }
        if (!isFound) {
            output.println("NG");
        }
        closeReader();
    } main {
//        openFile();
        openConsole();
        int n = readInt();
        int start = readInt();
        int end = readInt();
        boolean isFound = false;
        for (int i = start; i <= end; i++) {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        }
        if (!isFound) {
            output.println("NG");
        }
        closeReader();
    } openConsole() openConsole int n = readInt(); n readInt() readInt int start = readInt(); start readInt() readInt int end = readInt(); end readInt() readInt boolean isFound = false; isFound false for (int i = start; i <= end; i++) {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        } int i = start; int i = start; i start i <= end i end i++ i++ i {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        } {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        } if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            } i % n == 0 i % n i n 0 {
                output.println("OK");
                isFound = true;
                break;
            } output.println("OK") output.println output "OK" isFound = true isFound true break; if (!isFound) {
            output.println("NG");
        } !isFound isFound {
            output.println("NG");
        } output.println("NG") output.println output "NG" closeReader() closeReader String[] args args private static void solveC() throws IOException {
        int numTest = readInt();
        for (int i = 0; i < numTest; i++) {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        }
    } solveC {
        int numTest = readInt();
        for (int i = 0; i < numTest; i++) {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        }
    } int numTest = readInt(); numTest readInt() readInt for (int i = 0; i < numTest; i++) {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        } int i = 0; int i = 0; i 0 i < numTest i numTest i++ i++ i {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        } {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        } int a = readInt(); a readInt() readInt int b = readInt(); b readInt() readInt int c = readInt(); c readInt() readInt int aRes = 0 aRes 0 bRes = 0 bRes 0 cRes = 0 cRes 0 count = Integer.MAX_VALUE; count Integer.MAX_VALUE Integer Integer.MAX_VALUE for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            } int aIter = 1; int aIter = 1; aIter 1 aIter <= 2 * a aIter 2 * a 2 a aIter++ aIter++ aIter {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            } {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            } for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                } int bIter = aIter; int bIter = aIter; bIter aIter bIter <= 2 * b bIter 2 * b 2 b bIter += aIter bIter += aIter bIter aIter {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                } {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                } int cLow = bIter * (c / bIter); cLow bIter * (c / bIter) bIter (c / bIter) c bIter int cHigh = cLow + bIter; cHigh cLow + bIter cLow bIter int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b); aAndBDist Math.abs(aIter - a) + Math.abs(bIter - b) Math.abs(aIter - a) Math.abs Math aIter - a aIter a Math.abs(bIter - b) Math.abs Math bIter - b bIter b int firstSum = aAndBDist + Math.abs(cLow - c); firstSum aAndBDist + Math.abs(cLow - c) aAndBDist Math.abs(cLow - c) Math.abs Math cLow - c cLow c int secondSum = aAndBDist + Math.abs(cHigh - c); secondSum aAndBDist + Math.abs(cHigh - c) aAndBDist Math.abs(cHigh - c) Math.abs Math cHigh - c cHigh c if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    } firstSum < count firstSum count {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    } aRes = aIter aRes aIter bRes = bIter bRes bIter cRes = cLow cRes cLow count = firstSum count firstSum if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    } secondSum < count secondSum count {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    } aRes = aIter aRes aIter bRes = bIter bRes bIter cRes = cHigh cRes cHigh count = secondSum count secondSum output.println(count) output.println output count output.println(aRes + " " + bRes + " " + cRes) output.println output aRes + " " + bRes + " " + cRes " " bRes aRes + " " + bRes + " " + cRes aRes " " bRes " " cRes private static String readString() throws IOException {
        return input.nextLine();
    } readString {
        return input.nextLine();
    } return input.nextLine(); input.nextLine() input.nextLine input private static int readInt() throws IOException {
        return input.nextInt();
    } readInt {
        return input.nextInt();
    } return input.nextInt(); input.nextInt() input.nextInt input private static void swap(int[] data, int i, int j) {
        int temp = data[i];
        data[i] = data[j];
        data[j] = temp;
    } swap {
        int temp = data[i];
        data[i] = data[j];
        data[j] = temp;
    } int temp = data[i]; temp data[i] data i data[i] = data[j] data[i] data i data[j] data j data[j] = temp data[j] data j temp int[] data data int i i int j j private static void openConsole() {
        input = new FastScanner(System.in);
        output = new PrintWriter(System.out);
    } openConsole {
        input = new FastScanner(System.in);
        output = new PrintWriter(System.out);
    } input = new FastScanner(System.in) input new FastScanner(System.in) output = new PrintWriter(System.out) output new PrintWriter(System.out) private static void openFile() throws FileNotFoundException {
        ClassLoader classLoader = Main.class.getClassLoader();
        File myFile = new File(classLoader.getResource("input.txt").getFile());
        input = new FastScanner(new FileInputStream(myFile));
        output = new PrintWriter(System.out);
    } openFile {
        ClassLoader classLoader = Main.class.getClassLoader();
        File myFile = new File(classLoader.getResource("input.txt").getFile());
        input = new FastScanner(new FileInputStream(myFile));
        output = new PrintWriter(System.out);
    } ClassLoader classLoader = Main.class.getClassLoader(); classLoader Main.class.getClassLoader() Main.class.getClassLoader Main.class Main.class File myFile = new File(classLoader.getResource("input.txt").getFile()); myFile new File(classLoader.getResource("input.txt").getFile()) input = new FastScanner(new FileInputStream(myFile)) input new FastScanner(new FileInputStream(myFile)) output = new PrintWriter(System.out) output new PrintWriter(System.out) private static void closeReader() {
        output.flush();
        output.close();
    } closeReader {
        output.flush();
        output.close();
    } output.flush() output.flush output output.close() output.close output static class Pair {
        int id, count;

        Pair(Integer id, Integer count) {
            this.id = id;
            this.count = count;
        }
    } Pair int id id count; count Pair(Integer id, Integer count) {
            this.id = id;
            this.count = count;
        } Pair {
            this.id = id;
            this.count = count;
        } this.id = id this.id this this.id id this.count = count this.count this this.count count Integer id id Integer count count static class FastScanner {
        StringTokenizer st;
        BufferedReader br;

        FastScanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        private String next() throws IOException {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        }

        boolean hasNext() throws IOException {
            return br.ready() || (st != null && st.hasMoreTokens());
        }

        int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        String nextLine() throws IOException {
            return br.readLine();
        }

        boolean hasNextLine() throws IOException {
            return br.ready();
        }
    } FastScanner StringTokenizer st; st BufferedReader br; br FastScanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        } FastScanner {
            br = new BufferedReader(new InputStreamReader(s));
        } br = new BufferedReader(new InputStreamReader(s)) br new BufferedReader(new InputStreamReader(s)) InputStream s s private String next() throws IOException {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        } next {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        } while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            } st == null || !st.hasMoreTokens() st == null st null !st.hasMoreTokens() st.hasMoreTokens() st.hasMoreTokens st {
                st = new StringTokenizer(br.readLine());
            } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st boolean hasNext() throws IOException {
            return br.ready() || (st != null && st.hasMoreTokens());
        } hasNext {
            return br.ready() || (st != null && st.hasMoreTokens());
        } return br.ready() || (st != null && st.hasMoreTokens()); br.ready() || (st != null && st.hasMoreTokens()) br.ready() br.ready br (st != null && st.hasMoreTokens()) st != null st null st.hasMoreTokens() st.hasMoreTokens st int nextInt() throws IOException {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() throws IOException {
            return Long.parseLong(next());
        } nextLong {
            return Long.parseLong(next());
        } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() throws IOException {
            return Double.parseDouble(next());
        } nextDouble {
            return Double.parseDouble(next());
        } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine() throws IOException {
            return br.readLine();
        } nextLine {
            return br.readLine();
        } return br.readLine(); br.readLine() br.readLine br boolean hasNextLine() throws IOException {
            return br.ready();
        } hasNextLine {
            return br.ready();
        } return br.ready(); br.ready() br.ready br public class Main {
    private static FastScanner input;
    private static PrintWriter output;

    public static void main(String[] args) throws IOException {
//        openFile();
        openConsole();
        int n = readInt();
        int start = readInt();
        int end = readInt();
        boolean isFound = false;
        for (int i = start; i <= end; i++) {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        }
        if (!isFound) {
            output.println("NG");
        }
        closeReader();
    }


    private static void solveC() throws IOException {
        int numTest = readInt();
        for (int i = 0; i < numTest; i++) {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        }
    }

    private static String readString() throws IOException {
        return input.nextLine();
    }

    private static int readInt() throws IOException {
        return input.nextInt();
    }

    private static void swap(int[] data, int i, int j) {
        int temp = data[i];
        data[i] = data[j];
        data[j] = temp;
    }

    private static void openConsole() {
        input = new FastScanner(System.in);
        output = new PrintWriter(System.out);
    }

    private static void openFile() throws FileNotFoundException {
        ClassLoader classLoader = Main.class.getClassLoader();
        File myFile = new File(classLoader.getResource("input.txt").getFile());
        input = new FastScanner(new FileInputStream(myFile));
        output = new PrintWriter(System.out);
    }

    private static void closeReader() {
        output.flush();
        output.close();
    }

    static class Pair {
        int id, count;

        Pair(Integer id, Integer count) {
            this.id = id;
            this.count = count;
        }
    }

    static class FastScanner {
        StringTokenizer st;
        BufferedReader br;

        FastScanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        private String next() throws IOException {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        }

        boolean hasNext() throws IOException {
            return br.ready() || (st != null && st.hasMoreTokens());
        }

        int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        String nextLine() throws IOException {
            return br.readLine();
        }

        boolean hasNextLine() throws IOException {
            return br.ready();
        }
    }
} public class Main {
    private static FastScanner input;
    private static PrintWriter output;

    public static void main(String[] args) throws IOException {
//        openFile();
        openConsole();
        int n = readInt();
        int start = readInt();
        int end = readInt();
        boolean isFound = false;
        for (int i = start; i <= end; i++) {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        }
        if (!isFound) {
            output.println("NG");
        }
        closeReader();
    }


    private static void solveC() throws IOException {
        int numTest = readInt();
        for (int i = 0; i < numTest; i++) {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        }
    }

    private static String readString() throws IOException {
        return input.nextLine();
    }

    private static int readInt() throws IOException {
        return input.nextInt();
    }

    private static void swap(int[] data, int i, int j) {
        int temp = data[i];
        data[i] = data[j];
        data[j] = temp;
    }

    private static void openConsole() {
        input = new FastScanner(System.in);
        output = new PrintWriter(System.out);
    }

    private static void openFile() throws FileNotFoundException {
        ClassLoader classLoader = Main.class.getClassLoader();
        File myFile = new File(classLoader.getResource("input.txt").getFile());
        input = new FastScanner(new FileInputStream(myFile));
        output = new PrintWriter(System.out);
    }

    private static void closeReader() {
        output.flush();
        output.close();
    }

    static class Pair {
        int id, count;

        Pair(Integer id, Integer count) {
            this.id = id;
            this.count = count;
        }
    }

    static class FastScanner {
        StringTokenizer st;
        BufferedReader br;

        FastScanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        private String next() throws IOException {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        }

        boolean hasNext() throws IOException {
            return br.ready() || (st != null && st.hasMoreTokens());
        }

        int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        String nextLine() throws IOException {
            return br.readLine();
        }

        boolean hasNextLine() throws IOException {
            return br.ready();
        }
    }
} Main
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.stream.Collectors;

public class Main {
    private static FastScanner input;
    private static PrintWriter output;

    public static void main(String[] args) throws IOException {
//        openFile();
        openConsole();
        int n = readInt();
        int start = readInt();
        int end = readInt();
        boolean isFound = false;
        for (int i = start; i <= end; i++) {
            if (i % n == 0) {
                output.println("OK");
                isFound = true;
                break;
            }
        }
        if (!isFound) {
            output.println("NG");
        }
        closeReader();
    }


    private static void solveC() throws IOException {
        int numTest = readInt();
        for (int i = 0; i < numTest; i++) {
            int a = readInt();
            int b = readInt();
            int c = readInt();
            int aRes = 0, bRes = 0, cRes = 0, count = Integer.MAX_VALUE;
            for (int aIter = 1; aIter <= 2 * a; aIter++) {
                for (int bIter = aIter; bIter <= 2 * b; bIter += aIter) {
                    int cLow = bIter * (c / bIter);
                    int cHigh = cLow + bIter;
                    int aAndBDist = Math.abs(aIter - a) + Math.abs(bIter - b);
                    int firstSum = aAndBDist + Math.abs(cLow - c);
                    int secondSum = aAndBDist + Math.abs(cHigh - c);
                    if (firstSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cLow;
                        count = firstSum;
                    }
                    if (secondSum < count) {
                        aRes = aIter;
                        bRes = bIter;
                        cRes = cHigh;
                        count = secondSum;
                    }
                }
            }
            output.println(count);
            output.println(aRes + " " + bRes + " " + cRes);
        }
    }

    private static String readString() throws IOException {
        return input.nextLine();
    }

    private static int readInt() throws IOException {
        return input.nextInt();
    }

    private static void swap(int[] data, int i, int j) {
        int temp = data[i];
        data[i] = data[j];
        data[j] = temp;
    }

    private static void openConsole() {
        input = new FastScanner(System.in);
        output = new PrintWriter(System.out);
    }

    private static void openFile() throws FileNotFoundException {
        ClassLoader classLoader = Main.class.getClassLoader();
        File myFile = new File(classLoader.getResource("input.txt").getFile());
        input = new FastScanner(new FileInputStream(myFile));
        output = new PrintWriter(System.out);
    }

    private static void closeReader() {
        output.flush();
        output.close();
    }

    static class Pair {
        int id, count;

        Pair(Integer id, Integer count) {
            this.id = id;
            this.count = count;
        }
    }

    static class FastScanner {
        StringTokenizer st;
        BufferedReader br;

        FastScanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        private String next() throws IOException {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        }

        boolean hasNext() throws IOException {
            return br.ready() || (st != null && st.hasMoreTokens());
        }

        int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        String nextLine() throws IOException {
            return br.readLine();
        }

        boolean hasNextLine() throws IOException {
            return br.ready();
        }
    }
}
