#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(),(x).end()
typedef long long ll;
// #include<C:\Users\J\Desktop\AC\athead.h>
#define showa(v) for(int iii = 0; iii < v.size(); iii++){ cout << v[iii] << " ";} cout << endl;
#define show(iiii) cout << iiii << endl; 
#define shows(iiiii) cout << iiiii << " ";
#include<iostream>
#include<string>
#include<vector>
#include<stdio.h>
#include <cmath>
#include <cstdlib>
#include <cassert>
#include <algorithm>
#include <set>
#include <deque>
#include <numeric>
#include<tuple>
#include <utility>
#include <map>
#include<stack>
#include<queue>
#include <cassert>
using namespace std;

 
int main(){
        int k, a, b;
    cin >> k >> a >> b;
    int bb = b/k;
    if(bb == 0){
        cout << "NG" << endl;

    }
    else{
        int aa = a/k;
        if( a % k == 0){
            cout << "OK" << endl;
        }
        else{
            if(aa < bb){
                cout << "OK" << endl;
            }
            else{
                cout << "NG" <<endl;
            }
        }
    }
}