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>

#define ll          long long
#define pb          push_back
#define ppb         pop_back
#define BigInt      __int128
#define endl        '\n'
#define mii         map<ll int,ll int>
#define pii         pair<ll int,ll int>
#define vi          vector<ll int>
#define all(a)      (a).begin(),(a).end()
#define F           first
#define S           second
#define sz(x)       (ll int)x.size()
#define hell        1000000007
#define lbnd        lower_bound
#define ubnd        upper_bound
#define bs          binary_search
#define mp          make_pair
#define sim         template < class c
#define ris         return * this
#define dor         > debug & operator <<
#define eni(x)      sim > typename \
  enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {

using namespace std;

sim > struct rge {c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug 
{
	~debug() 
	{ 
		cerr<<endl; 
	}
	eni(!=) cerr << boolalpha << i; ris; }
	eni(==) ris << range(begin(i), end(i)); }
	sim, class b dor(pair < b, c > d) 
	{
		ris << "(" << d.first << ", " << d.second << ")";
	}
	sim dor(rge<c> d) 
	{
	  	*this << "[";
	  	for (auto it = d.b; it != d.e; ++it)
	    	*this << ", " + 2 * (it == d.b) << *it;
	  	ris << "]";
	}
};
#define fuck(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

#define N  100005

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int TESTS=1;
	// cin>>TESTS;
	while(TESTS--)
	{
		ll int k,a,b;
		cin>>k>>a>>b;
		for(ll int i=0;i<=100000;i++)
		{
			if(a<=i*k && i*k<=b)
			{
				cout<<"OK";
				return 0;
			}
		}
		cout<<"NG"<<endl;
	}
	return 0;
}