

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.InputStreamReader;


public class Main {

    public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);

        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        boolean flag = false;
        for (int i = A; i <=B  ; i++) {
            if(i%K == 0){
                flag = true;
                break;
            }
        }

        if (flag){
            System.out.println("OK");
        }else System.out.println("NG");
    }

    public static int MaxTwo(int x, int y){
        return ((x > y)?x:y);
    }
    public static int MaxThree(int x, int y, int z){
        return MaxTwo(MaxTwo(x,y),z);
    }
    public static int MinTwo(int x, int y){
        return ((x < y)?x:y);
    }
    public static int MinThree(int x, int y, int z){
        return MinTwo(MinTwo(x,y),z);
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

        public int[] nextIntArray(int size){
            int arr[] =new int[size];
            for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            }
            return arr;
        }

    }
}

 import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.Arrays; Arrays java.util import java.util.StringTokenizer; StringTokenizer java.util import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

    public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);

        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        boolean flag = false;
        for (int i = A; i <=B  ; i++) {
            if(i%K == 0){
                flag = true;
                break;
            }
        }

        if (flag){
            System.out.println("OK");
        }else System.out.println("NG");
    }

    public static int MaxTwo(int x, int y){
        return ((x > y)?x:y);
    }
    public static int MaxThree(int x, int y, int z){
        return MaxTwo(MaxTwo(x,y),z);
    }
    public static int MinTwo(int x, int y){
        return ((x < y)?x:y);
    }
    public static int MinThree(int x, int y, int z){
        return MinTwo(MinTwo(x,y),z);
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

        public int[] nextIntArray(int size){
            int arr[] =new int[size];
            for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            }
            return arr;
        }

    }
} Main public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);

        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        boolean flag = false;
        for (int i = A; i <=B  ; i++) {
            if(i%K == 0){
                flag = true;
                break;
            }
        }

        if (flag){
            System.out.println("OK");
        }else System.out.println("NG");
    } main {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);

        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        boolean flag = false;
        for (int i = A; i <=B  ; i++) {
            if(i%K == 0){
                flag = true;
                break;
            }
        }

        if (flag){
            System.out.println("OK");
        }else System.out.println("NG");
    } InputReader in = new InputReader(System.in); in new InputReader(System.in) PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) int K = in.nextInt(); K in.nextInt() in.nextInt in int A = in.nextInt(); A in.nextInt() in.nextInt in int B = in.nextInt(); B in.nextInt() in.nextInt in boolean flag = false; flag false for (int i = A; i <=B  ; i++) {
            if(i%K == 0){
                flag = true;
                break;
            }
        } int i = A; int i = A; i A i <=B i B i++ i++ i {
            if(i%K == 0){
                flag = true;
                break;
            }
        } {
            if(i%K == 0){
                flag = true;
                break;
            }
        } if(i%K == 0){
                flag = true;
                break;
            } i%K == 0 i%K i K 0 {
                flag = true;
                break;
            } flag = true flag true break; if (flag){
            System.out.println("OK");
        }else System.out.println("NG"); flag {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" System.out.println("NG") System.out.println System.out System System.out "NG" String[] args args public static int MaxTwo(int x, int y){
        return ((x > y)?x:y);
    } MaxTwo {
        return ((x > y)?x:y);
    } return ((x > y)?x:y); ((x > y)?x:y) (x > y) x y x y int x x int y y public static int MaxThree(int x, int y, int z){
        return MaxTwo(MaxTwo(x,y),z);
    } MaxThree {
        return MaxTwo(MaxTwo(x,y),z);
    } return MaxTwo(MaxTwo(x,y),z); MaxTwo(MaxTwo(x,y),z) MaxTwo MaxTwo(x,y) MaxTwo x y z int x x int y y int z z public static int MinTwo(int x, int y){
        return ((x < y)?x:y);
    } MinTwo {
        return ((x < y)?x:y);
    } return ((x < y)?x:y); ((x < y)?x:y) (x < y) x y x y int x x int y y public static int MinThree(int x, int y, int z){
        return MinTwo(MinTwo(x,y),z);
    } MinThree {
        return MinTwo(MinTwo(x,y),z);
    } return MinTwo(MinTwo(x,y),z); MinTwo(MinTwo(x,y),z) MinTwo MinTwo(x,y) MinTwo x y z int x x int y y int z z static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

        public int[] nextIntArray(int size){
            int arr[] =new int[size];
            for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            }
            return arr;
        }

    } InputReader public BufferedReader reader; reader public StringTokenizer tokenizer; tokenizer public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } InputReader {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } reader = new BufferedReader(new InputStreamReader(stream), 32768) reader new BufferedReader(new InputStreamReader(stream), 32768) tokenizer = null tokenizer null InputStream stream stream public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } next {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    tokenizer = new StringTokenizer(reader.readLine());
                } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public int[] nextIntArray(int size){
            int arr[] =new int[size];
            for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            }
            return arr;
        } nextIntArray {
            int arr[] =new int[size];
            for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            }
            return arr;
        } int arr[] =new int[size]; arr new int[size] size for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            } int i = 0; int i = 0; i 0 i < size i size i++ i++ i {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            } {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            } arr[i] = Integer.parseInt(next()) arr[i] arr i Integer.parseInt(next()) Integer.parseInt Integer next() next return arr; arr int size size public class Main {

    public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);

        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        boolean flag = false;
        for (int i = A; i <=B  ; i++) {
            if(i%K == 0){
                flag = true;
                break;
            }
        }

        if (flag){
            System.out.println("OK");
        }else System.out.println("NG");
    }

    public static int MaxTwo(int x, int y){
        return ((x > y)?x:y);
    }
    public static int MaxThree(int x, int y, int z){
        return MaxTwo(MaxTwo(x,y),z);
    }
    public static int MinTwo(int x, int y){
        return ((x < y)?x:y);
    }
    public static int MinThree(int x, int y, int z){
        return MinTwo(MinTwo(x,y),z);
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

        public int[] nextIntArray(int size){
            int arr[] =new int[size];
            for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            }
            return arr;
        }

    }
} public class Main {

    public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);

        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        boolean flag = false;
        for (int i = A; i <=B  ; i++) {
            if(i%K == 0){
                flag = true;
                break;
            }
        }

        if (flag){
            System.out.println("OK");
        }else System.out.println("NG");
    }

    public static int MaxTwo(int x, int y){
        return ((x > y)?x:y);
    }
    public static int MaxThree(int x, int y, int z){
        return MaxTwo(MaxTwo(x,y),z);
    }
    public static int MinTwo(int x, int y){
        return ((x < y)?x:y);
    }
    public static int MinThree(int x, int y, int z){
        return MinTwo(MinTwo(x,y),z);
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

        public int[] nextIntArray(int size){
            int arr[] =new int[size];
            for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            }
            return arr;
        }

    }
} Main


import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.InputStreamReader;


public class Main {

    public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);

        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        boolean flag = false;
        for (int i = A; i <=B  ; i++) {
            if(i%K == 0){
                flag = true;
                break;
            }
        }

        if (flag){
            System.out.println("OK");
        }else System.out.println("NG");
    }

    public static int MaxTwo(int x, int y){
        return ((x > y)?x:y);
    }
    public static int MaxThree(int x, int y, int z){
        return MaxTwo(MaxTwo(x,y),z);
    }
    public static int MinTwo(int x, int y){
        return ((x < y)?x:y);
    }
    public static int MinThree(int x, int y, int z){
        return MinTwo(MinTwo(x,y),z);
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

        public int[] nextIntArray(int size){
            int arr[] =new int[size];
            for (int i = 0; i < size; i++) {
                arr[i] = Integer.parseInt(next());
//                sum = sum + in.nextInt();
            }
            return arr;
        }

    }
}


