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;
        int multiple=0;
        boolean flag = true;
        while(flag){
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        }
        ;
    }
} 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;
        int multiple=0;
        boolean flag = true;
        while(flag){
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        }
        ;
    }
} 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;
        int multiple=0;
        boolean flag = true;
        while(flag){
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        }
        ;
    } main {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        int count =0;
        int multiple=0;
        boolean flag = true;
        while(flag){
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        }
        ;
    } 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 int multiple=0; multiple 0 boolean flag = true; flag true while(flag){
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        } flag {
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        } count++ count multiple=K*count multiple K*count K count if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            } A<=multiple&& multiple<=B A<=multiple A multiple multiple<=B multiple B {
                System.out.println("OK");
                break;
            } System.out.println("OK") System.out.println System.out System System.out "OK" break; if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            } multiple>=1000 multiple 1000 {
                flag=false;
                System.out.println("NG");
                break;
            } flag=false flag false System.out.println("NG") System.out.println System.out System System.out "NG" break; 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;
        int multiple=0;
        boolean flag = true;
        while(flag){
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        }
        ;
    }
} 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;
        int multiple=0;
        boolean flag = true;
        while(flag){
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        }
        ;
    }
} Main
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;
        int multiple=0;
        boolean flag = true;
        while(flag){
            count++;
            multiple=K*count;
            if(A<=multiple&& multiple<=B){
                System.out.println("OK");
                break;
            }
            if(multiple>=1000) {
                flag=false;
                System.out.println("NG");
                break;
            }
        }
        ;
    }
}