import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        
        String a = "NG";
        
        for(int i=A;i<=B;i++){
            if(i%K == 0){
                a = "OK";
                break;
            }
        }
        System.out.println(a);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        
        String a = "NG";
        
        for(int i=A;i<=B;i++){
            if(i%K == 0){
                a = "OK";
                break;
            }
        }
        System.out.println(a);
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        
        String a = "NG";
        
        for(int i=A;i<=B;i++){
            if(i%K == 0){
                a = "OK";
                break;
            }
        }
        System.out.println(a);
    } main {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        
        String a = "NG";
        
        for(int i=A;i<=B;i++){
            if(i%K == 0){
                a = "OK";
                break;
            }
        }
        System.out.println(a);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int K = sc.nextInt(); K sc.nextInt() sc.nextInt sc int A = sc.nextInt(); A sc.nextInt() sc.nextInt sc int B = sc.nextInt(); B sc.nextInt() sc.nextInt sc String a = "NG"; a "NG" for(int i=A;i<=B;i++){
            if(i%K == 0){
                a = "OK";
                break;
            }
        } int i=A; int i=A; i A i<=B i B i++ i++ i {
            if(i%K == 0){
                a = "OK";
                break;
            }
        } {
            if(i%K == 0){
                a = "OK";
                break;
            }
        } if(i%K == 0){
                a = "OK";
                break;
            } i%K == 0 i%K i K 0 {
                a = "OK";
                break;
            } a = "OK" a "OK" break; System.out.println(a) System.out.println System.out System System.out a String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        
        String a = "NG";
        
        for(int i=A;i<=B;i++){
            if(i%K == 0){
                a = "OK";
                break;
            }
        }
        System.out.println(a);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        
        String a = "NG";
        
        for(int i=A;i<=B;i++){
            if(i%K == 0){
                a = "OK";
                break;
            }
        }
        System.out.println(a);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        
        String a = "NG";
        
        for(int i=A;i<=B;i++){
            if(i%K == 0){
                a = "OK";
                break;
            }
        }
        System.out.println(a);
    }
}
