import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int K = scanner.nextInt();
		int A = scanner.nextInt();
		int B = scanner.nextInt();
		List<Integer> X = new ArrayList<Integer>();
		List<Integer> Y = new ArrayList<Integer>();
		for(int i = 0; i*K <= B; i++) {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		}
		if(X.size()==0) {
			System.out.println("NG");
		}else {
			System.out.println("OK");
		}
	}
} import java.util.ArrayList; ArrayList java.util import java.util.List; List java.util 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 A = scanner.nextInt();
		int B = scanner.nextInt();
		List<Integer> X = new ArrayList<Integer>();
		List<Integer> Y = new ArrayList<Integer>();
		for(int i = 0; i*K <= B; i++) {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		}
		if(X.size()==0) {
			System.out.println("NG");
		}else {
			System.out.println("OK");
		}
	}
} Main public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int K = scanner.nextInt();
		int A = scanner.nextInt();
		int B = scanner.nextInt();
		List<Integer> X = new ArrayList<Integer>();
		List<Integer> Y = new ArrayList<Integer>();
		for(int i = 0; i*K <= B; i++) {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		}
		if(X.size()==0) {
			System.out.println("NG");
		}else {
			System.out.println("OK");
		}
	} main {
		Scanner scanner = new Scanner(System.in);
		int K = scanner.nextInt();
		int A = scanner.nextInt();
		int B = scanner.nextInt();
		List<Integer> X = new ArrayList<Integer>();
		List<Integer> Y = new ArrayList<Integer>();
		for(int i = 0; i*K <= B; i++) {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		}
		if(X.size()==0) {
			System.out.println("NG");
		}else {
			System.out.println("OK");
		}
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int K = scanner.nextInt(); K scanner.nextInt() scanner.nextInt scanner int A = scanner.nextInt(); A scanner.nextInt() scanner.nextInt scanner int B = scanner.nextInt(); B scanner.nextInt() scanner.nextInt scanner List<Integer> X = new ArrayList<Integer>(); X new ArrayList<Integer>() List<Integer> Y = new ArrayList<Integer>(); Y new ArrayList<Integer>() for(int i = 0; i*K <= B; i++) {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		} int i = 0; int i = 0; i 0 i*K <= B i*K i K B i++ i++ i {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		} {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		} if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			} i*K >= A i*K i K A {
			X.add(i*K);
			} X.add(i*K) X.add X i*K i K {
			Y.add(i*K);
			} Y.add(i*K) Y.add Y i*K i K if(X.size()==0) {
			System.out.println("NG");
		}else {
			System.out.println("OK");
		} X.size()==0 X.size() X.size X 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 scanner = new Scanner(System.in);
		int K = scanner.nextInt();
		int A = scanner.nextInt();
		int B = scanner.nextInt();
		List<Integer> X = new ArrayList<Integer>();
		List<Integer> Y = new ArrayList<Integer>();
		for(int i = 0; i*K <= B; i++) {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		}
		if(X.size()==0) {
			System.out.println("NG");
		}else {
			System.out.println("OK");
		}
	}
} public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int K = scanner.nextInt();
		int A = scanner.nextInt();
		int B = scanner.nextInt();
		List<Integer> X = new ArrayList<Integer>();
		List<Integer> Y = new ArrayList<Integer>();
		for(int i = 0; i*K <= B; i++) {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		}
		if(X.size()==0) {
			System.out.println("NG");
		}else {
			System.out.println("OK");
		}
	}
} Main
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int K = scanner.nextInt();
		int A = scanner.nextInt();
		int B = scanner.nextInt();
		List<Integer> X = new ArrayList<Integer>();
		List<Integer> Y = new ArrayList<Integer>();
		for(int i = 0; i*K <= B; i++) {
			if(i*K >= A) {
			X.add(i*K);
			}else {
			Y.add(i*K);
			}
		}
		if(X.size()==0) {
			System.out.println("NG");
		}else {
			System.out.println("OK");
		}
	}
}
