import java.util.Scanner;
	public class Main{
		public static void main(String args[]) {
			Scanner scan=new Scanner(System.in) ;
			int K=scan.nextInt();
			int A=scan.nextInt();
			int B=scan.nextInt();
			int num=0;
			int i=A/K;
			int j=i*K;
			for(int k=j;k<=B;k=k+K) {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			}
		if(num==0) {	
			System.out.println("NG");
		}
		else {System.out.println("OK");
		}
		}
	} import java.util.Scanner; Scanner java.util public class Main{
		public static void main(String args[]) {
			Scanner scan=new Scanner(System.in) ;
			int K=scan.nextInt();
			int A=scan.nextInt();
			int B=scan.nextInt();
			int num=0;
			int i=A/K;
			int j=i*K;
			for(int k=j;k<=B;k=k+K) {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			}
		if(num==0) {	
			System.out.println("NG");
		}
		else {System.out.println("OK");
		}
		}
	} Main public static void main(String args[]) {
			Scanner scan=new Scanner(System.in) ;
			int K=scan.nextInt();
			int A=scan.nextInt();
			int B=scan.nextInt();
			int num=0;
			int i=A/K;
			int j=i*K;
			for(int k=j;k<=B;k=k+K) {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			}
		if(num==0) {	
			System.out.println("NG");
		}
		else {System.out.println("OK");
		}
		} main {
			Scanner scan=new Scanner(System.in) ;
			int K=scan.nextInt();
			int A=scan.nextInt();
			int B=scan.nextInt();
			int num=0;
			int i=A/K;
			int j=i*K;
			for(int k=j;k<=B;k=k+K) {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			}
		if(num==0) {	
			System.out.println("NG");
		}
		else {System.out.println("OK");
		}
		} Scanner scan=new Scanner(System.in) ; scan new Scanner(System.in) int K=scan.nextInt(); K scan.nextInt() scan.nextInt scan int A=scan.nextInt(); A scan.nextInt() scan.nextInt scan int B=scan.nextInt(); B scan.nextInt() scan.nextInt scan int num=0; num 0 int i=A/K; i A/K A K int j=i*K; j i*K i K for(int k=j;k<=B;k=k+K) {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			} int k=j; int k=j; k j k<=B k B k=k+K k=k+K k k+K k K {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			} {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			} if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {} k>=A&&k<=B k>=A k A k<=B k B {
					num=1;
					break;
				} num=1 num 1 break; {} if(num==0) {	
			System.out.println("NG");
		}
		else {System.out.println("OK");
		} num==0 num 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 scan=new Scanner(System.in) ;
			int K=scan.nextInt();
			int A=scan.nextInt();
			int B=scan.nextInt();
			int num=0;
			int i=A/K;
			int j=i*K;
			for(int k=j;k<=B;k=k+K) {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			}
		if(num==0) {	
			System.out.println("NG");
		}
		else {System.out.println("OK");
		}
		}
	} public class Main{
		public static void main(String args[]) {
			Scanner scan=new Scanner(System.in) ;
			int K=scan.nextInt();
			int A=scan.nextInt();
			int B=scan.nextInt();
			int num=0;
			int i=A/K;
			int j=i*K;
			for(int k=j;k<=B;k=k+K) {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			}
		if(num==0) {	
			System.out.println("NG");
		}
		else {System.out.println("OK");
		}
		}
	} Main
import java.util.Scanner;
	public class Main{
		public static void main(String args[]) {
			Scanner scan=new Scanner(System.in) ;
			int K=scan.nextInt();
			int A=scan.nextInt();
			int B=scan.nextInt();
			int num=0;
			int i=A/K;
			int j=i*K;
			for(int k=j;k<=B;k=k+K) {
				if(k>=A&&k<=B) {
					num=1;
					break;
				}
				else {}
			}
		if(num==0) {	
			System.out.println("NG");
		}
		else {System.out.println("OK");
		}
		}
	}
