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