import java.util.*;
import java.io.*;

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();

    if (a % k == 0 || b % k == 0){
      System.out.println("OK");
      return;
    }

      int rem = a % k;
      int temp = a-rem;
      temp += k;
      for(int i=temp; i<b; i+=k){
        if(temp > a){
          System.out.println("OK");
          return;
        }
      }
      System.out.println("NG");
  }
} import java.util.*; util.* java import java.io.*; io.* java 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();

    if (a % k == 0 || b % k == 0){
      System.out.println("OK");
      return;
    }

      int rem = a % k;
      int temp = a-rem;
      temp += k;
      for(int i=temp; i<b; i+=k){
        if(temp > a){
          System.out.println("OK");
          return;
        }
      }
      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();

    if (a % k == 0 || b % k == 0){
      System.out.println("OK");
      return;
    }

      int rem = a % k;
      int temp = a-rem;
      temp += k;
      for(int i=temp; i<b; i+=k){
        if(temp > a){
          System.out.println("OK");
          return;
        }
      }
      System.out.println("NG");
  } main {
    Scanner sc = new Scanner(System.in);
    int k = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();

    if (a % k == 0 || b % k == 0){
      System.out.println("OK");
      return;
    }

      int rem = a % k;
      int temp = a-rem;
      temp += k;
      for(int i=temp; i<b; i+=k){
        if(temp > a){
          System.out.println("OK");
          return;
        }
      }
      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 if (a % k == 0 || b % k == 0){
      System.out.println("OK");
      return;
    } a % k == 0 || b % k == 0 a % k == 0 a % k a k 0 b % k == 0 b % k b k 0 {
      System.out.println("OK");
      return;
    } System.out.println("OK") System.out.println System.out System System.out "OK" return; int rem = a % k; rem a % k a k int temp = a-rem; temp a-rem a rem temp += k temp k for(int i=temp; i<b; i+=k){
        if(temp > a){
          System.out.println("OK");
          return;
        }
      } int i=temp; int i=temp; i temp i<b i b i+=k i+=k i k {
        if(temp > a){
          System.out.println("OK");
          return;
        }
      } {
        if(temp > a){
          System.out.println("OK");
          return;
        }
      } if(temp > a){
          System.out.println("OK");
          return;
        } temp > a temp a {
          System.out.println("OK");
          return;
        } System.out.println("OK") System.out.println System.out System System.out "OK" return; 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();

    if (a % k == 0 || b % k == 0){
      System.out.println("OK");
      return;
    }

      int rem = a % k;
      int temp = a-rem;
      temp += k;
      for(int i=temp; i<b; i+=k){
        if(temp > a){
          System.out.println("OK");
          return;
        }
      }
      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();

    if (a % k == 0 || b % k == 0){
      System.out.println("OK");
      return;
    }

      int rem = a % k;
      int temp = a-rem;
      temp += k;
      for(int i=temp; i<b; i+=k){
        if(temp > a){
          System.out.println("OK");
          return;
        }
      }
      System.out.println("NG");
  }
} Main
import java.util.*;
import java.io.*;

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();

    if (a % k == 0 || b % k == 0){
      System.out.println("OK");
      return;
    }

      int rem = a % k;
      int temp = a-rem;
      temp += k;
      for(int i=temp; i<b; i+=k){
        if(temp > a){
          System.out.println("OK");
          return;
        }
      }
      System.out.println("NG");
  }
}
