import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		int K = cin.nextInt();
		int A = cin.nextInt();
		int B = cin.nextInt();
		
		int start = A/K;
		int end = B/K;
		
		for(int i = start;i<=end;i++) {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		}
		
		System.out.println("NG");
		

	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		int K = cin.nextInt();
		int A = cin.nextInt();
		int B = cin.nextInt();
		
		int start = A/K;
		int end = B/K;
		
		for(int i = start;i<=end;i++) {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		}
		
		System.out.println("NG");
		

	}

} Main public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		int K = cin.nextInt();
		int A = cin.nextInt();
		int B = cin.nextInt();
		
		int start = A/K;
		int end = B/K;
		
		for(int i = start;i<=end;i++) {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		}
		
		System.out.println("NG");
		

	} main {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		int K = cin.nextInt();
		int A = cin.nextInt();
		int B = cin.nextInt();
		
		int start = A/K;
		int end = B/K;
		
		for(int i = start;i<=end;i++) {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		}
		
		System.out.println("NG");
		

	} Scanner cin = new Scanner(System.in); cin new Scanner(System.in) int K = cin.nextInt(); K cin.nextInt() cin.nextInt cin int A = cin.nextInt(); A cin.nextInt() cin.nextInt cin int B = cin.nextInt(); B cin.nextInt() cin.nextInt cin int start = A/K; start A/K A K int end = B/K; end B/K B K for(int i = start;i<=end;i++) {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		} int i = start; int i = start; i start i<=end i end i++ i++ i {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		} {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		} int target = i*K; target i*K i K if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			} A<=target&&B>=target A<=target A target B>=target B target {
				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) {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		int K = cin.nextInt();
		int A = cin.nextInt();
		int B = cin.nextInt();
		
		int start = A/K;
		int end = B/K;
		
		for(int i = start;i<=end;i++) {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		}
		
		System.out.println("NG");
		

	}

} public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		int K = cin.nextInt();
		int A = cin.nextInt();
		int B = cin.nextInt();
		
		int start = A/K;
		int end = B/K;
		
		for(int i = start;i<=end;i++) {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		}
		
		System.out.println("NG");
		

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		int K = cin.nextInt();
		int A = cin.nextInt();
		int B = cin.nextInt();
		
		int start = A/K;
		int end = B/K;
		
		for(int i = start;i<=end;i++) {
			int target = i*K;
			if(A<=target&&B>=target) {
				System.out.println("OK");
				return;
			}
		}
		
		System.out.println("NG");
		

	}

}
