import java.util.*;
import java.math.BigInteger;

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 x = A / K;
    int X = (x+1)*K;
    
    if(A == x*K) {
      System.out.println("OK");
    } else if(A<X && X<=B) {
      System.out.println("OK");
    } else {
      System.out.println("NG");
    }
  }
} import java.util.*; util.* java import java.math.BigInteger; BigInteger java.math 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 x = A / K;
    int X = (x+1)*K;
    
    if(A == x*K) {
      System.out.println("OK");
    } else if(A<X && X<=B) {
      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 x = A / K;
    int X = (x+1)*K;
    
    if(A == x*K) {
      System.out.println("OK");
    } else if(A<X && X<=B) {
      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 x = A / K;
    int X = (x+1)*K;
    
    if(A == x*K) {
      System.out.println("OK");
    } else if(A<X && X<=B) {
      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 x = A / K; x A / K A K int X = (x+1)*K; X (x+1)*K (x+1) x 1 K if(A == x*K) {
      System.out.println("OK");
    } else if(A<X && X<=B) {
      System.out.println("OK");
    } else {
      System.out.println("NG");
    } A == x*K A x*K x K {
      System.out.println("OK");
    } System.out.println("OK") System.out.println System.out System System.out "OK" if(A<X && X<=B) {
      System.out.println("OK");
    } else {
      System.out.println("NG");
    } A<X && X<=B A<X A X X<=B X B {
      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 x = A / K;
    int X = (x+1)*K;
    
    if(A == x*K) {
      System.out.println("OK");
    } else if(A<X && X<=B) {
      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 x = A / K;
    int X = (x+1)*K;
    
    if(A == x*K) {
      System.out.println("OK");
    } else if(A<X && X<=B) {
      System.out.println("OK");
    } else {
      System.out.println("NG");
    }
  }
} Main
import java.util.*;
import java.math.BigInteger;

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 x = A / K;
    int X = (x+1)*K;
    
    if(A == x*K) {
      System.out.println("OK");
    } else if(A<X && X<=B) {
      System.out.println("OK");
    } else {
      System.out.println("NG");
    }
  }
}