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: Accepted)

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = ll(1e12);
const ll mod = ll(1e9) + 7;
#define rep0(i,n) for(ll (i) = 0; (i) < (n); ++(i))
#define rrep0(i,n) for(ll (i) = (n) - 1; (i) >= 0; --(i))
#define rep1(i,n) for(ll (i) = 1; (i) <= (n); ++(i))
#define rrep1(i,n) for(ll (i) = (n); (i) >= 1; --(i))
#define nfor(i,a,b) for(ll (i) = (a); (i) < (b); ++(i))
#define pf(x) cout << (x) << endl
#define all(x) (x).begin(),(x).end()
#define yes pf("Yes")
#define no pf("No")

ll gcd(ll a,ll b){
    if(a < b)swap(a, b);
    if(b == 0) return a;
    return gcd(b,a%b);
}

ll lcm(ll a,ll b){
    ll g = gcd(a,b);
    return a / g * b;
}

ll factorial(ll n){
    ll t = 1;
    rep1(i, n){
        t *= i;
        t %= mod;
    }
    return t;
}

ll power(ll a, ll b){
    a %= mod;
    if(b == 0){
        return 1;
    }
    ll ans = power(a, b / 2);
    ans = ans * ans % mod;
    if(b % 2 == 1){
        ans = ans * a % mod;
    }
    return ans;
}

ll combination(ll a, ll b){
    if((a == b) || (b == 0)){
        return 1;
    }
    if(a < b) return 0;
    ll ans = 1;
    for(ll i = 0; i < b; i++) {
        ans *= (a - i);
        ans /= (i + 1);
        ans %= mod;
    }
    return ans;
}

int main(){
    ll k,a,b;
    cin >> k >> a >> b;
    nfor(i, a, b + 1){
        if(i % k == 0){
            pf("OK");
            return 0;
        }
    }
    pf("NG");
    return 0;
}