import java.util.*;

public class Main{
    public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
	final int X = sc.nextInt();
    int X2 = X;
    int A = sc.nextInt();
    int B = sc.nextInt();
      while(X2 <= 1000){
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      }
      System.out.println("NG");
	}
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
	final int X = sc.nextInt();
    int X2 = X;
    int A = sc.nextInt();
    int B = sc.nextInt();
      while(X2 <= 1000){
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      }
      System.out.println("NG");
	}
} Main public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
	final int X = sc.nextInt();
    int X2 = X;
    int A = sc.nextInt();
    int B = sc.nextInt();
      while(X2 <= 1000){
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      }
      System.out.println("NG");
	} main {
	Scanner sc = new Scanner(System.in);
	final int X = sc.nextInt();
    int X2 = X;
    int A = sc.nextInt();
    int B = sc.nextInt();
      while(X2 <= 1000){
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      }
      System.out.println("NG");
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) final int X = sc.nextInt(); X sc.nextInt() sc.nextInt sc int X2 = X; X2 X int A = sc.nextInt(); A sc.nextInt() sc.nextInt sc int B = sc.nextInt(); B sc.nextInt() sc.nextInt sc while(X2 <= 1000){
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      } X2 <= 1000 X2 1000 {
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      } if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        } X2 >= A && X2 <= B X2 >= A X2 A X2 <= B X2 B {
          System.out.println("OK");
          return;
        } System.out.println("OK") System.out.println System.out System System.out "OK" return; X2 += X X2 X 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);
	final int X = sc.nextInt();
    int X2 = X;
    int A = sc.nextInt();
    int B = sc.nextInt();
      while(X2 <= 1000){
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      }
      System.out.println("NG");
	}
} public class Main{
    public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
	final int X = sc.nextInt();
    int X2 = X;
    int A = sc.nextInt();
    int B = sc.nextInt();
      while(X2 <= 1000){
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      }
      System.out.println("NG");
	}
} Main
import java.util.*;

public class Main{
    public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
	final int X = sc.nextInt();
    int X2 = X;
    int A = sc.nextInt();
    int B = sc.nextInt();
      while(X2 <= 1000){
        if(X2 >= A && X2 <= B){
          System.out.println("OK");
          return;
        }
        X2 += X;
        
      }
      System.out.println("NG");
	}
}
