#include <ext/pb_ds/assoc_container.hpp>
#include <bits/stdc++.h>
using namespace std;
using namespace __gnu_pbds;
template <class c, class cmp = less<c> > using ordered_set = tree<c, null_type, cmp, rb_tree_tag, tree_order_statistics_node_update>;
#define IOS ios_base::sync_with_stdio(false);cin.tie(NULL); 

#define ld long double


#define TRACE
#ifdef TRACE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');cerr.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...);
}
#else
#define trace(...) 1
#endif
template<class T> ostream& operator<<(ostream &os, vector<T> V) {os << "[ "; for(auto v : V) os << v << " "; return os << "]";}
template<class L, class R> ostream& operator<<(ostream &os, pair<L,R> P) {return os << "(" << P.first << "," << P.second << ")";}
template <typename T,typename U>pair<T,U> operator+(const pair<T,U> & l,const std::pair<T,U> & r) { return {l.first+r.first,l.second+r.second};}

typedef long long int ll;
#define int ll
#define endl '\n'
const ll mod =1e9+7;
const ll MAX_NODES =200001;
const ll MAX_LOG =50;
const ll inf = 1e18+123;
const int maxn = 2000001;
int32_t main()
{

   IOS
  int k,a,b;
  cin>>k>>a>>b;
  if(a%k == 0)
    {
      cout<<"OK"<<endl;
      return 0;
    }
  int mul = a+(k-a%k);
   if(mul<=b){
     cout<<"OK"<<endl;
   }
   else{
     cout<<"NG";
   }
  
} 
