import java.util.*;
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();
        for(int i = 1; i <= 1000; i++){
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        }  
    }
} import java.util.*; util.* java 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();
        for(int i = 1; i <= 1000; i++){
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        }  
    }
} 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();
        for(int i = 1; i <= 1000; i++){
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        }  
    } main {
		Scanner sc = new Scanner(System.in);
		int K = sc.nextInt(); 
        int A = sc.nextInt();
        int B = sc.nextInt();
        for(int i = 1; i <= 1000; i++){
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        }  
    } 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 for(int i = 1; i <= 1000; i++){
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        } int i = 1; int i = 1; i 1 i <= 1000 i 1000 i++ i++ i {
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        } {
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        } int ans = K * i; ans K * i K i if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          } ans >= A && ans <= B ans >= A ans A ans <= B ans B {
            System.out.println("OK");
            break;
          } System.out.println("OK") System.out.println System.out System System.out "OK" break; if(ans >= B){
            System.out.println("NG");
            break;
          } ans >= B ans B {
            System.out.println("NG");
            break;
          } System.out.println("NG") System.out.println System.out System System.out "NG" break; 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();
        for(int i = 1; i <= 1000; i++){
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        }  
    }
} 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();
        for(int i = 1; i <= 1000; i++){
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        }  
    }
} Main
import java.util.*;
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();
        for(int i = 1; i <= 1000; i++){
          int ans = K * i;
          if(ans >= A && ans <= B){
            System.out.println("OK");
            break;
          }else if(ans >= B){
            System.out.println("NG");
            break;
          }
        }  
    }
}