#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC target("avx,avx2,fma")
#include<bits/stdc++.h>
#define F first
#define S second
#define vec vector
#define ms multiset
#define pb push_back
#define pll pair<ll,ll>
#define pdd pair<ld, ld>
#define pq priority_queue
#define umap unordered_map
#define uset unordered_set
#define pii pair<int, int>
#define pnn pair<Node*, Node*>
#define uid uniform_int_distribution
#define FILE ifstream in("sumsqr.in");ofstream out("sumsqr.out");
#define fast cin.tie(0);cout.tie(0);cin.sync_with_stdio(0);cout.sync_with_stdio(0);
using namespace std;
typedef string str;
typedef long long ll;
typedef long double ld;
typedef unsigned int uint;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

int main() {
    fast;
    ll k,l,r; cin>>k>>l>>r;
    ll fl = 0;
    for(; l<=r; l++) fl |= l%k==0;
    cout<<(fl ? "OK" : "NG");
}