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 cnt = 0;
      for(int i=A; i<=B; i++){
		if(i%K == 0){
			cnt = cnt+1;
			}
		}
        if (cnt >= 1 ) {
            System.out.println("OK");
        }
        else {
            System.out.println("NG");
        }
        scan.close();
    }
} 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 cnt = 0;
      for(int i=A; i<=B; i++){
		if(i%K == 0){
			cnt = cnt+1;
			}
		}
        if (cnt >= 1 ) {
            System.out.println("OK");
        }
        else {
            System.out.println("NG");
        }
        scan.close();
    }
} 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 cnt = 0;
      for(int i=A; i<=B; i++){
		if(i%K == 0){
			cnt = cnt+1;
			}
		}
        if (cnt >= 1 ) {
            System.out.println("OK");
        }
        else {
            System.out.println("NG");
        }
        scan.close();
    } main {
        Scanner scan = new Scanner(System.in);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();
      	int cnt = 0;
      for(int i=A; i<=B; i++){
		if(i%K == 0){
			cnt = cnt+1;
			}
		}
        if (cnt >= 1 ) {
            System.out.println("OK");
        }
        else {
            System.out.println("NG");
        }
        scan.close();
    } 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 cnt = 0; cnt 0 for(int i=A; i<=B; i++){
		if(i%K == 0){
			cnt = cnt+1;
			}
		} int i=A; int i=A; i A i<=B i B i++ i++ i {
		if(i%K == 0){
			cnt = cnt+1;
			}
		} {
		if(i%K == 0){
			cnt = cnt+1;
			}
		} if(i%K == 0){
			cnt = cnt+1;
			} i%K == 0 i%K i K 0 {
			cnt = cnt+1;
			} cnt = cnt+1 cnt cnt+1 cnt 1 if (cnt >= 1 ) {
            System.out.println("OK");
        }
        else {
            System.out.println("NG");
        } cnt >= 1 cnt 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" scan.close() scan.close scan 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 cnt = 0;
      for(int i=A; i<=B; i++){
		if(i%K == 0){
			cnt = cnt+1;
			}
		}
        if (cnt >= 1 ) {
            System.out.println("OK");
        }
        else {
            System.out.println("NG");
        }
        scan.close();
    }
} 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 cnt = 0;
      for(int i=A; i<=B; i++){
		if(i%K == 0){
			cnt = cnt+1;
			}
		}
        if (cnt >= 1 ) {
            System.out.println("OK");
        }
        else {
            System.out.println("NG");
        }
        scan.close();
    }
} 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 cnt = 0;
      for(int i=A; i<=B; i++){
		if(i%K == 0){
			cnt = cnt+1;
			}
		}
        if (cnt >= 1 ) {
            System.out.println("OK");
        }
        else {
            System.out.println("NG");
        }
        scan.close();
    }
}