
#include<bits/stdc++.h>


using namespace std;

using ll   = long long;
using ii   = pair   < int , int >;
using i3   = pair   < int , ii  >;
using li   = pair   < ll  , int >;
using lii  = pair   < ll  , ii  >;
using pll  = pair   < ll  , ll  >;
using vi   = vector < int       >;
using vl   = vector < ll        >;
using vii  = vector < ii        >;
using vli  = vector < li        >;
using vpll = vector < pll       >;
using vi3  = vector < i3        >;
using vlii = vector < lii       >;


const int N = 2e5 + 5;
const ll INF = 1e17 + 7;
const double eps = 1e-9 , PI = acos(-1);



int n , m;


void solve(int testCase){

    int k; scanf("%d" , &k);
    scanf("%d %d" , &n , &m);

    for(int i = n ; i <= m ; i ++) {
            if(i % k == 0) {
                    printf("OK\n");
                    return;
            }
    }

    printf("NG\n");

}

main(){

    int t = 1;
    // scanf("%d" , &t);

    for(int testCase = 1 ; testCase <= t ; testCase ++){
            solve(testCase);
    }

    return 0;
}
