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();
		
      	int divide = a/k;
      if (a%k==0) {System.out.println("OK");}
      else if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");}	
    
	}
} 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();
		
      	int divide = a/k;
      if (a%k==0) {System.out.println("OK");}
      else if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");}	
    
	}
} 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();
		
      	int divide = a/k;
      if (a%k==0) {System.out.println("OK");}
      else if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");}	
    
	} main {
		
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
        int a = sc.nextInt();
		int b = sc.nextInt();
		
      	int divide = a/k;
      if (a%k==0) {System.out.println("OK");}
      else if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");}	
    
	} 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 int divide = a/k; divide a/k a k if (a%k==0) {System.out.println("OK");}
      else if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");} a%k==0 a%k a k 0 {System.out.println("OK");} System.out.println("OK") System.out.println System.out System System.out "OK" if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");} ((divide+1)*k) <= b ((divide+1)*k) (divide+1) divide 1 k b {System.out.println("OK");} System.out.println("OK") System.out.println System.out System System.out "OK" {System.out.println("NG");} System.out.println("NG") System.out.println System.out System System.out "NG" 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();
		
      	int divide = a/k;
      if (a%k==0) {System.out.println("OK");}
      else if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");}	
    
	}
} 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();
		
      	int divide = a/k;
      if (a%k==0) {System.out.println("OK");}
      else if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");}	
    
	}
} 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();
		
      	int divide = a/k;
      if (a%k==0) {System.out.println("OK");}
      else if (((divide+1)*k) <= b)
      {System.out.println("OK");}
      else {System.out.println("NG");}	
    
	}
}