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);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

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

            boolean ok = false;
            for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            }
            if (!ok)
                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);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

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

            boolean ok = false;
            for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            }
            if (!ok)
                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);
        TaskA solver = new TaskA();
        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);
        TaskA solver = new TaskA();
        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) TaskA solver = new TaskA(); solver new TaskA() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class TaskA {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int k = in.nextInt();
            in.nextLine();
            int A = in.nextInt();
            int B = in.nextInt();

            boolean ok = false;
            for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            }
            if (!ok)
                out.println("NG");
        }

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

            boolean ok = false;
            for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            }
            if (!ok)
                out.println("NG");
        } solve {
            int k = in.nextInt();
            in.nextLine();
            int A = in.nextInt();
            int B = in.nextInt();

            boolean ok = false;
            for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            }
            if (!ok)
                out.println("NG");
        } int k = in.nextInt(); k in.nextInt() in.nextInt in in.nextLine() in.nextLine in int A = in.nextInt(); A in.nextInt() in.nextInt in int B = in.nextInt(); B in.nextInt() in.nextInt in boolean ok = false; ok false for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            } int i = A; int i = A; i A i <= B i B i++ i++ i {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            } {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            } if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                } i % k == 0 i % k i k 0 {
                    out.println("OK");
                    ok = true;
                    break;
                } out.println("OK") out.println out "OK" ok = true ok true break; if (!ok)
                out.println("NG"); !ok ok 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);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

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

            boolean ok = false;
            for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            }
            if (!ok)
                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);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

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

            boolean ok = false;
            for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            }
            if (!ok)
                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);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

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

            boolean ok = false;
            for (int i = A; i <= B; i++) {
                if (i % k == 0) {
                    out.println("OK");
                    ok = true;
                    break;
                }
            }
            if (!ok)
                out.println("NG");
        }

    }
}

