import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws IOException {
        MyReader reader = new MyReader();
        int k = reader.readInt();
        int[] ab = reader.readInts(" ");
        System.out.println(problem165a(k, ab[0], ab[1]));
    }

    private static String problem165a(int k, int a, int b) {
        for (int i = a; i <= b; i++) {
            if (i % k == 0) return "OK";
        }
        return "NG";
    }

    private static class MyReader {
        private final BufferedReader br;
        private MyReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

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

        private int readInt() throws IOException {
            return Integer.parseInt(readString());
        }

        private String[] readStrings(String regex) throws IOException {
            return readString().split(regex);
        }

        private int[] readInts(String regex) throws IOException {
            String[] strings = readStrings(regex);
            int[] ints = new int[strings.length];
            for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            }
            return ints;
        }
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

    public static void main(String[] args) throws IOException {
        MyReader reader = new MyReader();
        int k = reader.readInt();
        int[] ab = reader.readInts(" ");
        System.out.println(problem165a(k, ab[0], ab[1]));
    }

    private static String problem165a(int k, int a, int b) {
        for (int i = a; i <= b; i++) {
            if (i % k == 0) return "OK";
        }
        return "NG";
    }

    private static class MyReader {
        private final BufferedReader br;
        private MyReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

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

        private int readInt() throws IOException {
            return Integer.parseInt(readString());
        }

        private String[] readStrings(String regex) throws IOException {
            return readString().split(regex);
        }

        private int[] readInts(String regex) throws IOException {
            String[] strings = readStrings(regex);
            int[] ints = new int[strings.length];
            for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            }
            return ints;
        }
    }
} Main public static void main(String[] args) throws IOException {
        MyReader reader = new MyReader();
        int k = reader.readInt();
        int[] ab = reader.readInts(" ");
        System.out.println(problem165a(k, ab[0], ab[1]));
    } main {
        MyReader reader = new MyReader();
        int k = reader.readInt();
        int[] ab = reader.readInts(" ");
        System.out.println(problem165a(k, ab[0], ab[1]));
    } MyReader reader = new MyReader(); reader new MyReader() int k = reader.readInt(); k reader.readInt() reader.readInt reader int[] ab = reader.readInts(" "); ab reader.readInts(" ") reader.readInts reader " " System.out.println(problem165a(k, ab[0], ab[1])) System.out.println System.out System System.out problem165a(k, ab[0], ab[1]) problem165a k ab[0] ab 0 ab[1] ab 1 String[] args args private static String problem165a(int k, int a, int b) {
        for (int i = a; i <= b; i++) {
            if (i % k == 0) return "OK";
        }
        return "NG";
    } problem165a {
        for (int i = a; i <= b; i++) {
            if (i % k == 0) return "OK";
        }
        return "NG";
    } for (int i = a; i <= b; i++) {
            if (i % k == 0) return "OK";
        } int i = a; int i = a; i a i <= b i b i++ i++ i {
            if (i % k == 0) return "OK";
        } {
            if (i % k == 0) return "OK";
        } if (i % k == 0) return "OK"; i % k == 0 i % k i k 0 return "OK"; "OK" return "NG"; "NG" int k k int a a int b b private static class MyReader {
        private final BufferedReader br;
        private MyReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

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

        private int readInt() throws IOException {
            return Integer.parseInt(readString());
        }

        private String[] readStrings(String regex) throws IOException {
            return readString().split(regex);
        }

        private int[] readInts(String regex) throws IOException {
            String[] strings = readStrings(regex);
            int[] ints = new int[strings.length];
            for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            }
            return ints;
        }
    } MyReader private final BufferedReader br; br private MyReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        } MyReader {
            br = new BufferedReader(new InputStreamReader(System.in));
        } br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) private String readString() throws IOException {
            return br.readLine();
        } readString {
            return br.readLine();
        } return br.readLine(); br.readLine() br.readLine br private int readInt() throws IOException {
            return Integer.parseInt(readString());
        } readInt {
            return Integer.parseInt(readString());
        } return Integer.parseInt(readString()); Integer.parseInt(readString()) Integer.parseInt Integer readString() readString private String[] readStrings(String regex) throws IOException {
            return readString().split(regex);
        } readStrings {
            return readString().split(regex);
        } return readString().split(regex); readString().split(regex) readString().split readString() readString regex String regex regex private int[] readInts(String regex) throws IOException {
            String[] strings = readStrings(regex);
            int[] ints = new int[strings.length];
            for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            }
            return ints;
        } readInts {
            String[] strings = readStrings(regex);
            int[] ints = new int[strings.length];
            for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            }
            return ints;
        } String[] strings = readStrings(regex); strings readStrings(regex) readStrings regex int[] ints = new int[strings.length]; ints new int[strings.length] strings.length strings strings.length for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            } int i = 0; int i = 0; i 0 i < ints.length i ints.length ints ints.length i++ i++ i {
                ints[i] = Integer.parseInt(strings[i]);
            } {
                ints[i] = Integer.parseInt(strings[i]);
            } ints[i] = Integer.parseInt(strings[i]) ints[i] ints i Integer.parseInt(strings[i]) Integer.parseInt Integer strings[i] strings i return ints; ints String regex regex public class Main {

    public static void main(String[] args) throws IOException {
        MyReader reader = new MyReader();
        int k = reader.readInt();
        int[] ab = reader.readInts(" ");
        System.out.println(problem165a(k, ab[0], ab[1]));
    }

    private static String problem165a(int k, int a, int b) {
        for (int i = a; i <= b; i++) {
            if (i % k == 0) return "OK";
        }
        return "NG";
    }

    private static class MyReader {
        private final BufferedReader br;
        private MyReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

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

        private int readInt() throws IOException {
            return Integer.parseInt(readString());
        }

        private String[] readStrings(String regex) throws IOException {
            return readString().split(regex);
        }

        private int[] readInts(String regex) throws IOException {
            String[] strings = readStrings(regex);
            int[] ints = new int[strings.length];
            for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            }
            return ints;
        }
    }
} public class Main {

    public static void main(String[] args) throws IOException {
        MyReader reader = new MyReader();
        int k = reader.readInt();
        int[] ab = reader.readInts(" ");
        System.out.println(problem165a(k, ab[0], ab[1]));
    }

    private static String problem165a(int k, int a, int b) {
        for (int i = a; i <= b; i++) {
            if (i % k == 0) return "OK";
        }
        return "NG";
    }

    private static class MyReader {
        private final BufferedReader br;
        private MyReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

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

        private int readInt() throws IOException {
            return Integer.parseInt(readString());
        }

        private String[] readStrings(String regex) throws IOException {
            return readString().split(regex);
        }

        private int[] readInts(String regex) throws IOException {
            String[] strings = readStrings(regex);
            int[] ints = new int[strings.length];
            for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            }
            return ints;
        }
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws IOException {
        MyReader reader = new MyReader();
        int k = reader.readInt();
        int[] ab = reader.readInts(" ");
        System.out.println(problem165a(k, ab[0], ab[1]));
    }

    private static String problem165a(int k, int a, int b) {
        for (int i = a; i <= b; i++) {
            if (i % k == 0) return "OK";
        }
        return "NG";
    }

    private static class MyReader {
        private final BufferedReader br;
        private MyReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

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

        private int readInt() throws IOException {
            return Integer.parseInt(readString());
        }

        private String[] readStrings(String regex) throws IOException {
            return readString().split(regex);
        }

        private int[] readInts(String regex) throws IOException {
            String[] strings = readStrings(regex);
            int[] ints = new int[strings.length];
            for (int i = 0; i < ints.length; i++) {
                ints[i] = Integer.parseInt(strings[i]);
            }
            return ints;
        }
    }
}