import java.util.*;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
        int b = sc.nextInt();
		int c = sc.nextInt();
        int d = 0;
        for (int i= b; i<= c; i++) {
          if (i % a == 0) {
       		d = 1;
            }
        }
      if (d == 0) {
        System.out.println("NG");
        } else {
        System.out.println("OK");
      }
	}
} import java.util.*; util.* java public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
        int b = sc.nextInt();
		int c = sc.nextInt();
        int d = 0;
        for (int i= b; i<= c; i++) {
          if (i % a == 0) {
       		d = 1;
            }
        }
      if (d == 0) {
        System.out.println("NG");
        } else {
        System.out.println("OK");
      }
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
        int b = sc.nextInt();
		int c = sc.nextInt();
        int d = 0;
        for (int i= b; i<= c; i++) {
          if (i % a == 0) {
       		d = 1;
            }
        }
      if (d == 0) {
        System.out.println("NG");
        } else {
        System.out.println("OK");
      }
	} main {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
        int b = sc.nextInt();
		int c = sc.nextInt();
        int d = 0;
        for (int i= b; i<= c; i++) {
          if (i % a == 0) {
       		d = 1;
            }
        }
      if (d == 0) {
        System.out.println("NG");
        } else {
        System.out.println("OK");
      }
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int c = sc.nextInt(); c sc.nextInt() sc.nextInt sc int d = 0; d 0 for (int i= b; i<= c; i++) {
          if (i % a == 0) {
       		d = 1;
            }
        } int i= b; int i= b; i b i<= c i c i++ i++ i {
          if (i % a == 0) {
       		d = 1;
            }
        } {
          if (i % a == 0) {
       		d = 1;
            }
        } if (i % a == 0) {
       		d = 1;
            } i % a == 0 i % a i a 0 {
       		d = 1;
            } d = 1 d 1 if (d == 0) {
        System.out.println("NG");
        } else {
        System.out.println("OK");
      } d == 0 d 0 {
        System.out.println("NG");
        } System.out.println("NG") System.out.println System.out System System.out "NG" {
        System.out.println("OK");
      } System.out.println("OK") System.out.println System.out System System.out "OK" String[] args args public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
        int b = sc.nextInt();
		int c = sc.nextInt();
        int d = 0;
        for (int i= b; i<= c; i++) {
          if (i % a == 0) {
       		d = 1;
            }
        }
      if (d == 0) {
        System.out.println("NG");
        } else {
        System.out.println("OK");
      }
	}
} public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
        int b = sc.nextInt();
		int c = sc.nextInt();
        int d = 0;
        for (int i= b; i<= c; i++) {
          if (i % a == 0) {
       		d = 1;
            }
        }
      if (d == 0) {
        System.out.println("NG");
        } else {
        System.out.println("OK");
      }
	}
} Main
import java.util.*;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
        int b = sc.nextInt();
		int c = sc.nextInt();
        int d = 0;
        for (int i= b; i<= c; i++) {
          if (i % a == 0) {
       		d = 1;
            }
        }
      if (d == 0) {
        System.out.println("NG");
        } else {
        System.out.println("OK");
      }
	}
}