#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include<stack>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#include<unordered_map>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))

#define aut(r,v) for(auto r:v)
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define pc()  pop_back()
#define ull unsigned long long

#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
#define ll long long
#define endl '\n'
#define st stack<int>
#define q queue<int>
#define pq priority_queue<int>
#define vl vector<long long>
#define vi vector<int>
#define vb vector<bool>
#define vc vector<char>
#define pii pair<int,int>
#define mod 1000000007
#define ss second
#define ff first
#define vpii vector<pii>
#define vvi vector<vi>
#define vs vector<string>
#define un  unordered_map<int,int>
#define mii map<int,int>
#define Sort(a) sort(all(a))
#define ED(a) Sort(a), a.erase(unique(all(a)), a.end())//removing all duplicates
#define max3(a, b, c)   max(a, max(b, c))
#define min3(a, b, c)   min(a, min(b, c))
#define maxAll(a)       *max_element(all(a))
#define minAll(a)       *min_element(all(a))
#define allUpper(a)     transform(all(a), a.begin(), :: toupper)
#define allLower(a)     transform(all(a), a.begin(), :: tolower)
#define rev(a)          reverse(all(a))
#define ub              upper_bound
#define lb              lower_bound
#define adv(a,n)        advance(auto it:a,n)
#define RSort(a)         sort(a.rbegin(),a.rend()) //decending order
#define cnt(v,a)             count(all(v),a)
#define bs(v,a)           binary_search(all(v),a)
#define mmax(v)           *max_element(all(v))
#define mmin(v)           *min_element(all(v))
#define popcount(mask)                       __builtin_popcount(mask) // count set bit
#define popcountLL(mask)                     __builtin_popcountll(mask) // for long long
#define X real() // useful for working with #include <complex> for computational geometry
#define Y imag()
#define gcd __gcd

#define trace1(x)                           cerr << #x << ": " << x << endl;
#define trace2(x, y)                        cerr << #x << ": " << x << " | " << #y << ": " << y << endl;
#define trace3(x, y, z)                     cerr << #x << ": " << x << " | " << #y << ": " << y << " | " << #z << ": " << z << endl;
#define trace4(a, b, c, d)                  cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << endl;
#define trace5(a, b, c, d, e)               cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << " | " << #e << ": " << e << endl;
#define trace6(a, b, c, d, e, f)            cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << " | " << #e << ": " << e << " | " << #f << ": " << f << endl;


inline int setbit(int mask, int pos) { return mask |= (1 << pos); }
inline int resetbit(int mask, int pos) { return mask &= ~(1 << pos); }
inline int togglebit(int mask, int pos) { return mask ^= (1 << pos); }
inline bool checkbit(int mask, int pos) { return (bool)(mask & (1 << pos)); }
bool Pow2(int n) {
    return n && (!(n & (n - 1)));
}




int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int k;
    cin >> k;
    int a, b;
    cin >> a >> b;
    int flag = 0;
   for(int i=a;i<=b;i++) {
        if (i % k == 0) {flag = 1; break;
    }
    }
    if (flag == 1) cout << "OK" << endl;
    else cout << "NG" << endl;
}




Measured memory_bytes: 3104