#include<bits/stdc++.h>
#define MAX (int)(2e6+5)
#define PB push_back
#define MP make_pair
#define ll long long
#define pii pair<long long,long long>
#define sz(a) (int)a.size()
#define sl(a) scanf("%lld",&a)
#define sll(a,b) scanf("%lld%lld",&a,&b)
#define si(a) scanf("%d",&a)
#define sii(a,b) scanf("%d%d",&a,&b)
#define p1(a) cout<<"Check "<<a<<endl;
#define p2(a,b) cout<<"Check "<<a<<' '<<b<<endl;
#define p3(a,b,c) cout<<"Check "<<a<<' '<<b<<' '<<c<<endl;
#define forn(i,n) for(int i=0;i<int(n);i++)
#define fore(i,l,n) for(int i=int(l);i<int(n);i++)
#define clr(a) memset(a,0,sizeof(a))
#define MOD (int)(1e7+7)
#define INF (long long)(1e18)

using namespace std;

int main()
{
    //freopen("tt.txt","r",stdin);
    int test=1,i=0,n,m;
    //si(test);
    while(test--){
        int n;
        si(n);
        int a,b;
        sii(a,b);
        a--;
        if(b/n-a/n>0) cout<<"OK"<<endl;
        else cout<<"NG"<<endl;
    }
}
