import java.util.Scanner;

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 (Check(K, A, B) == true) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
	
	public static boolean Check(int k, int a, int b) {
		boolean result = false;
		
		for (int i = a; i <= b; i++) {
			if (i % k == 0) {
				result = true;
				break;
			}
		}
		
		return result;
	}
} import java.util.Scanner; Scanner java.util 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 (Check(K, A, B) == true) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
	
	public static boolean Check(int k, int a, int b) {
		boolean result = false;
		
		for (int i = a; i <= b; i++) {
			if (i % k == 0) {
				result = true;
				break;
			}
		}
		
		return result;
	}
} 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 (Check(K, A, B) == true) {
			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();
		
		if (Check(K, A, B) == true) {
			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 if (Check(K, A, B) == true) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		} Check(K, A, B) == true Check(K, A, B) Check K A B true {
			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 static boolean Check(int k, int a, int b) {
		boolean result = false;
		
		for (int i = a; i <= b; i++) {
			if (i % k == 0) {
				result = true;
				break;
			}
		}
		
		return result;
	} Check {
		boolean result = false;
		
		for (int i = a; i <= b; i++) {
			if (i % k == 0) {
				result = true;
				break;
			}
		}
		
		return result;
	} boolean result = false; result false for (int i = a; i <= b; i++) {
			if (i % k == 0) {
				result = true;
				break;
			}
		} int i = a; int i = a; i a i <= b i b i++ i++ i {
			if (i % k == 0) {
				result = true;
				break;
			}
		} {
			if (i % k == 0) {
				result = true;
				break;
			}
		} if (i % k == 0) {
				result = true;
				break;
			} i % k == 0 i % k i k 0 {
				result = true;
				break;
			} result = true result true break; return result; result int k k int a a int b b 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 (Check(K, A, B) == true) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
	
	public static boolean Check(int k, int a, int b) {
		boolean result = false;
		
		for (int i = a; i <= b; i++) {
			if (i % k == 0) {
				result = true;
				break;
			}
		}
		
		return result;
	}
} 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 (Check(K, A, B) == true) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
	
	public static boolean Check(int k, int a, int b) {
		boolean result = false;
		
		for (int i = a; i <= b; i++) {
			if (i % k == 0) {
				result = true;
				break;
			}
		}
		
		return result;
	}
} Main
import java.util.Scanner;

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 (Check(K, A, B) == true) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
	
	public static boolean Check(int k, int a, int b) {
		boolean result = false;
		
		for (int i = a; i <= b; i++) {
			if (i % k == 0) {
				result = true;
				break;
			}
		}
		
		return result;
	}
}
