
import java.io.InputStream;
import java.io.PrintStream;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        solve(System.in, System.out);
    }

    static void solve(InputStream is, PrintStream os) {
        // Your code here!
        Scanner scan = new Scanner(is);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();

        for(int i = A; i <= B; i++) {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        }

        os.println("NG");
    }
} import java.io.InputStream; InputStream java.io import java.io.PrintStream; PrintStream java.io import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        solve(System.in, System.out);
    }

    static void solve(InputStream is, PrintStream os) {
        // Your code here!
        Scanner scan = new Scanner(is);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();

        for(int i = A; i <= B; i++) {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        }

        os.println("NG");
    }
} Main public static void main(String[] args) throws Exception {
        solve(System.in, System.out);
    } main {
        solve(System.in, System.out);
    } solve(System.in, System.out) solve System.in System System.in System.out System System.out String[] args args static void solve(InputStream is, PrintStream os) {
        // Your code here!
        Scanner scan = new Scanner(is);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();

        for(int i = A; i <= B; i++) {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        }

        os.println("NG");
    } solve {
        // Your code here!
        Scanner scan = new Scanner(is);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();

        for(int i = A; i <= B; i++) {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        }

        os.println("NG");
    } Scanner scan = new Scanner(is); scan new Scanner(is) int K = scan.nextInt(); K scan.nextInt() scan.nextInt scan int A = scan.nextInt(); A scan.nextInt() scan.nextInt scan int B = scan.nextInt(); B scan.nextInt() scan.nextInt scan for(int i = A; i <= B; i++) {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        } int i = A; int i = A; i A i <= B i B i++ i++ i {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        } {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        } if (i % K == 0){
                os.println("OK");
                return;
            } i % K == 0 i % K i K 0 {
                os.println("OK");
                return;
            } os.println("OK") os.println os "OK" return; os.println("NG") os.println os "NG" InputStream is is PrintStream os os public class Main {
    public static void main(String[] args) throws Exception {
        solve(System.in, System.out);
    }

    static void solve(InputStream is, PrintStream os) {
        // Your code here!
        Scanner scan = new Scanner(is);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();

        for(int i = A; i <= B; i++) {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        }

        os.println("NG");
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        solve(System.in, System.out);
    }

    static void solve(InputStream is, PrintStream os) {
        // Your code here!
        Scanner scan = new Scanner(is);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();

        for(int i = A; i <= B; i++) {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        }

        os.println("NG");
    }
} Main

import java.io.InputStream;
import java.io.PrintStream;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        solve(System.in, System.out);
    }

    static void solve(InputStream is, PrintStream os) {
        // Your code here!
        Scanner scan = new Scanner(is);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();

        for(int i = A; i <= B; i++) {
            if (i % K == 0){
                os.println("OK");
                return;
            }
        }

        os.println("NG");
    }
}