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 <iostream>
#include <map>
#include <algorithm>
#include <string>
#include <vector> 
#include <numeric>
#include <cmath>
#include <queue>
#include <iomanip>
#include <functional>


#define CHMAX(a,b) a = std::max(a,b)
#define CHMIN(a,b) a = std::min(a,b)
#define MAXMIN(a,b,c) std::max(a,min(b,c))
#define CHABS(a) a = std::abs(a) 
#define COUT(a) std::cout << a << std::endl
#define CERR(a) std::cerr << a << std::endl
#define FOR(n) for(lli i = 0; i < n; i++)

using namespace std;
using lli = long long int;
using pll = pair<lli, lli>;
using tlll = tuple<lli, lli, lli>;
using vll = vector<lli>;

constexpr lli inf = 10000 * 10000;

lli mod197 = 1000000007LL;
lli INF = 10000000000000;

// ax + by = gcd(a,b) 最大公約数
template< typename T >
T extgcd(T a, T b, T& x, T& y) {
	T d = a;
	if (b != 0) {
		d = extgcd(b, a % b, y, x);
		y -= (a / b) * x;
	}
	else {
		x = 1;
		y = 0;
	}
	return d;
}

int main(void) {

	lli a, b, k;
	cin >> k >> a >> b;

	lli t = a % k;
	b = b - (a - t);
	a = t;

	if (a <= k && k <= b) {
		cout << "OK" << endl;
	}
	else {
		cout << "NG" << endl;
	}



	return 0;
}