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