import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		
		int K = scanner.nextInt();
		int from = scanner.nextInt();
		int to = scanner.nextInt();
		String result = "NG";
		
		scanner.close();
		
		for (int i = from; i <= to; i++) {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		}
		
		System.out.println(result);
	}

} import java.util.Scanner; Scanner java.util public class Main {
	
	public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		
		int K = scanner.nextInt();
		int from = scanner.nextInt();
		int to = scanner.nextInt();
		String result = "NG";
		
		scanner.close();
		
		for (int i = from; i <= to; i++) {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		}
		
		System.out.println(result);
	}

} Main public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		
		int K = scanner.nextInt();
		int from = scanner.nextInt();
		int to = scanner.nextInt();
		String result = "NG";
		
		scanner.close();
		
		for (int i = from; i <= to; i++) {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		}
		
		System.out.println(result);
	} main {
		
		Scanner scanner = new Scanner(System.in);
		
		int K = scanner.nextInt();
		int from = scanner.nextInt();
		int to = scanner.nextInt();
		String result = "NG";
		
		scanner.close();
		
		for (int i = from; i <= to; i++) {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		}
		
		System.out.println(result);
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int K = scanner.nextInt(); K scanner.nextInt() scanner.nextInt scanner int from = scanner.nextInt(); from scanner.nextInt() scanner.nextInt scanner int to = scanner.nextInt(); to scanner.nextInt() scanner.nextInt scanner String result = "NG"; result "NG" scanner.close() scanner.close scanner for (int i = from; i <= to; i++) {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		} int i = from; int i = from; i from i <= to i to i++ i++ i {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		} {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		} if (i % K == 0) {
				result = "OK";
				break;
			} else {
			} i % K == 0 i % K i K 0 {
				result = "OK";
				break;
			} result = "OK" result "OK" break; {
			} System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
	
	public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		
		int K = scanner.nextInt();
		int from = scanner.nextInt();
		int to = scanner.nextInt();
		String result = "NG";
		
		scanner.close();
		
		for (int i = from; i <= to; i++) {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		}
		
		System.out.println(result);
	}

} public class Main {
	
	public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		
		int K = scanner.nextInt();
		int from = scanner.nextInt();
		int to = scanner.nextInt();
		String result = "NG";
		
		scanner.close();
		
		for (int i = from; i <= to; i++) {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		}
		
		System.out.println(result);
	}

} Main
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		
		int K = scanner.nextInt();
		int from = scanner.nextInt();
		int to = scanner.nextInt();
		String result = "NG";
		
		scanner.close();
		
		for (int i = from; i <= to; i++) {
			
			if (i % K == 0) {
				result = "OK";
				break;
			} else {
			}

		}
		
		System.out.println(result);
	}

}
