import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        abc165_a solver = new abc165_a();
        solver.solve(1, in, out);
        out.close();
    }

    static class abc165_a {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int K = in.nextInt();
            int A = in.nextInt();
            int B = in.nextInt();

            for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            }
            out.println("NG");
        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        abc165_a solver = new abc165_a();
        solver.solve(1, in, out);
        out.close();
    }

    static class abc165_a {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int K = in.nextInt();
            int A = in.nextInt();
            int B = in.nextInt();

            for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            }
            out.println("NG");
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        abc165_a solver = new abc165_a();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        abc165_a solver = new abc165_a();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out Scanner in = new Scanner(inputStream); in new Scanner(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) abc165_a solver = new abc165_a(); solver new abc165_a() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class abc165_a {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int K = in.nextInt();
            int A = in.nextInt();
            int B = in.nextInt();

            for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            }
            out.println("NG");
        }

    } abc165_a public void solve(int testNumber, Scanner in, PrintWriter out) {
            int K = in.nextInt();
            int A = in.nextInt();
            int B = in.nextInt();

            for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            }
            out.println("NG");
        } solve {
            int K = in.nextInt();
            int A = in.nextInt();
            int B = in.nextInt();

            for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            }
            out.println("NG");
        } 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 for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            } int i = K; int i = K; i K i <= B i B i += K i += K i K {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            } {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            } if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                } (A <= i) && (i <= B) (A <= i) A i (i <= B) i B {
                    out.println("OK");
                    return;
                } out.println("OK") out.println out "OK" return; out.println("NG") out.println out "NG" int testNumber testNumber Scanner in in PrintWriter out out public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        abc165_a solver = new abc165_a();
        solver.solve(1, in, out);
        out.close();
    }

    static class abc165_a {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int K = in.nextInt();
            int A = in.nextInt();
            int B = in.nextInt();

            for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            }
            out.println("NG");
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        abc165_a solver = new abc165_a();
        solver.solve(1, in, out);
        out.close();
    }

    static class abc165_a {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int K = in.nextInt();
            int A = in.nextInt();
            int B = in.nextInt();

            for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            }
            out.println("NG");
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        abc165_a solver = new abc165_a();
        solver.solve(1, in, out);
        out.close();
    }

    static class abc165_a {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int K = in.nextInt();
            int A = in.nextInt();
            int B = in.nextInt();

            for (int i = K; i <= B; i += K) {
                if ((A <= i) && (i <= B)) {
                    out.println("OK");
                    return;
                }
            }
            out.println("NG");
        }

    }
}

