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