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 (Clang 10.0.0) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include <math.h>
typedef long long ll;

int main()
{
	ll A,B,N;
	scanf("%lld %lld %lld", &A,&B,&N);
	ll i = N;
	ll x;
	ll max = 0;
	ll sum = 0;
	while (i >= N - 4)
	{
		sum = (A*i/B) - A * (i/B);
		if (sum >= max)
		{
			x = i;
			max = sum;
		}
		i--;
	}
	printf("%lld\n",max);
	return (0);
}