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