//package atcoder;
 
import 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();
		int count = 0;
		for(int i=A;i<B+1;i++) {
			if(i%K == 0) {
				count ++;
			}
		}
		if(count>0) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
}
		 import java.util.*; util.* java 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();
		int count = 0;
		for(int i=A;i<B+1;i++) {
			if(i%K == 0) {
				count ++;
			}
		}
		if(count>0) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} 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();
		int count = 0;
		for(int i=A;i<B+1;i++) {
			if(i%K == 0) {
				count ++;
			}
		}
		if(count>0) {
			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();
		int count = 0;
		for(int i=A;i<B+1;i++) {
			if(i%K == 0) {
				count ++;
			}
		}
		if(count>0) {
			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 int count = 0; count 0 for(int i=A;i<B+1;i++) {
			if(i%K == 0) {
				count ++;
			}
		} int i=A; int i=A; i A i<B+1 i B+1 B 1 i++ i++ i {
			if(i%K == 0) {
				count ++;
			}
		} {
			if(i%K == 0) {
				count ++;
			}
		} if(i%K == 0) {
				count ++;
			} i%K == 0 i%K i K 0 {
				count ++;
			} count ++ count if(count>0) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		} count>0 count 0 {
			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 sc = new Scanner(System.in);
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		int count = 0;
		for(int i=A;i<B+1;i++) {
			if(i%K == 0) {
				count ++;
			}
		}
		if(count>0) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} 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();
		int count = 0;
		for(int i=A;i<B+1;i++) {
			if(i%K == 0) {
				count ++;
			}
		}
		if(count>0) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} Main
//package atcoder;
 
import 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();
		int count = 0;
		for(int i=A;i<B+1;i++) {
			if(i%K == 0) {
				count ++;
			}
		}
		if(count>0) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
}
		