
#include <iostream>
#include <iomanip> //! for setprecision(10)
#include <math.h>
#include <algorithm>
#include <functional> 
#include <string>
#include <vector>

#include <cstring>
#include <set>
#include <map>
#include <queue>
#include <utility>
#include <limits.h>

using namespace std;

typedef long long LL;

#define rep(i,n) for (int i = 0; i < (n); ++i)
#define dump(c) { for (auto it = c.begin(); it != c.end(); ++it) if (it == c.begin()) cout << *it; else cout << ' ' << *it; cout << endl; } 
#define dumpMap(m) { for (auto it: m) cout << it.first << "=>" << it.second << ' '; }

const int MOD = 1000000007;

int main()
{
	cin.tie(0);
	ios::sync_with_stdio(0);
    
    int K, A, B;
    cin >> K >> A >> B;

    bool ok= (A%K== 0 || B%K == 0 || A/K<B/K);

    cout << (ok ? "OK" : "NG") << endl;

    return 0;
}
