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