import java.util.*;
import java.math.BigDecimal;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        String ans = "NG";
        
        for(int i=a; i<=b; i++){
            if(i%k == 0){
                ans = "OK";
                break;
            }
        }
        
        System.out.println(ans);
    }
} import java.util.*; util.* java import java.math.BigDecimal; BigDecimal java.math public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        String ans = "NG";
        
        for(int i=a; i<=b; i++){
            if(i%k == 0){
                ans = "OK";
                break;
            }
        }
        
        System.out.println(ans);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        String ans = "NG";
        
        for(int i=a; i<=b; i++){
            if(i%k == 0){
                ans = "OK";
                break;
            }
        }
        
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        String ans = "NG";
        
        for(int i=a; i<=b; i++){
            if(i%k == 0){
                ans = "OK";
                break;
            }
        }
        
        System.out.println(ans);
    } 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 ans = "NG"; ans "NG" for(int i=a; i<=b; i++){
            if(i%k == 0){
                ans = "OK";
                break;
            }
        } int i=a; int i=a; i a i<=b i b i++ i++ i {
            if(i%k == 0){
                ans = "OK";
                break;
            }
        } {
            if(i%k == 0){
                ans = "OK";
                break;
            }
        } if(i%k == 0){
                ans = "OK";
                break;
            } i%k == 0 i%k i k 0 {
                ans = "OK";
                break;
            } ans = "OK" ans "OK" break; System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        String ans = "NG";
        
        for(int i=a; i<=b; i++){
            if(i%k == 0){
                ans = "OK";
                break;
            }
        }
        
        System.out.println(ans);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        String ans = "NG";
        
        for(int i=a; i<=b; i++){
            if(i%k == 0){
                ans = "OK";
                break;
            }
        }
        
        System.out.println(ans);
    }
} Main
import java.util.*;
import java.math.BigDecimal;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        String ans = "NG";
        
        for(int i=a; i<=b; i++){
            if(i%k == 0){
                ans = "OK";
                break;
            }
        }
        
        System.out.println(ans);
    }
}