Problem:
Score: 100 points

Problem Statement

Takahashi the Jumbo will practice golf.

His objective is to get a carry distance that is a multiple of K, while he can only make a carry distance of between A and B (inclusive).

If he can achieve the objective, print OK; if he cannot, print NG.

Constraints

All values in input are integers.

1 \leq A \leq B \leq 1000

1 \leq K \leq 1000

Input

Input is given from Standard Input in the following format:

K
A B

Output

If he can achieve the objective, print OK; if he cannot, print NG.

Sample Input 1

7
500 600

Sample Output 1

OK

Among the multiples of 7, for example, 567 lies between 500 and 600.

Sample Input 2

4
5 7

Sample Output 2

NG

No multiple of 4 lies between 5 and 7.

Sample Input 3

1
11 11

Sample Output 3

OK

Solution in C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include<stdlib.h>

int main(void) {

	int a,b,k;
	
	if(scanf("%d", &k) < 1) {
    fprintf(stderr, "error: ill-formed fraction.\n");
    exit(1);
}
	if(scanf("%d%d", &a,&b) < 2) {
    fprintf(stderr, "error: ill-formed fraction.\n");
    exit(1);
}
	
	if(b - a >= k){
		printf("OK");
	}else if(b < a || a < 1 || k < 1){
		printf("NG");
	}else{
		printf("NG");
	}
	return 0;
}