import java.util.Scanner;
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 cou = 0;
    for(int i=1; i<=b; i++) {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    }
    if(cou != 0){
    	System.out.println("OK");
    }else{
    	System.out.println("NG");
      }
}
} import java.util.Scanner; Scanner 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 cou = 0;
    for(int i=1; i<=b; i++) {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    }
    if(cou != 0){
    	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 cou = 0;
    for(int i=1; i<=b; i++) {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    }
    if(cou != 0){
    	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 cou = 0;
    for(int i=1; i<=b; i++) {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    }
    if(cou != 0){
    	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 cou = 0; cou 0 for(int i=1; i<=b; i++) {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    } int i=1; int i=1; i 1 i<=b i b i++ i++ i {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    } {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    } if(k*i>=a && k*i<=b) {
    		cou++;
    		} k*i>=a && k*i<=b k*i>=a k*i k i a k*i<=b k*i k i b {
    		cou++;
    		} cou++ cou if(cou != 0){
    	System.out.println("OK");
    }else{
    	System.out.println("NG");
      } cou != 0 cou 0 {
    	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 cou = 0;
    for(int i=1; i<=b; i++) {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    }
    if(cou != 0){
    	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 cou = 0;
    for(int i=1; i<=b; i++) {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    }
    if(cou != 0){
    	System.out.println("OK");
    }else{
    	System.out.println("NG");
      }
}
} Main
import java.util.Scanner;
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 cou = 0;
    for(int i=1; i<=b; i++) {
    	if(k*i>=a && k*i<=b) {
    		cou++;
    		}
    }
    if(cou != 0){
    	System.out.println("OK");
    }else{
    	System.out.println("NG");
      }
}
}