#include<bits/stdc++.h>
                #include <bitset>
                using namespace std;
                #define ll long long 
                #define ld long double
                #define MOD 1000000007
                #define mod9 1000000009
                #define fast ios_base :: sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);
                #define mp make_pair
                #define pb push_back
                #define ct ll t;cin>>t;while(t--)
                #define bi begin()
                #define ei end()
                #define fi first 
                #define se second  
                #define foe(i,a,b) for(ll i=a;i<b;i++)
                #define sz(s) s.size() 
                #define mem(a,s) memset(a,s,sizeof(a))    
                bool isPrime(ll n) 
                { 
                    // Corner case 
                    if (n <= 1) 
                        return false; 
                    
                    // Check from 2 to n-1 
                    for (ll i = 2; i*i <= n; i++) 
                        if (n % i == 0) 
                            return false; 
                    
                    return true; 
                }
                long long binpow(long long a, long long b) {
                    long long res = 1;
                    while (b > 0) {
                        if (b & 1)
                            res = (res%MOD) * (a%MOD);
                        a = (a%MOD) * (a%MOD);
                        b >>= 1;
                    }
                    return res%MOD;
                }
        
                // bool compare(const pair<ll,ll>&a,const pair<ll,ll>&b)
                // {
                //     return (a.se<b.se);
                // }
                ll lcm(ll a,ll b)
                {
                    return(a*b)/__gcd(a,b);
                }
                // vector<ll>s;
                set<ll>s1;
                void SieveOfEratosthenes() 
                {  
                    ll n=1000005;
                    bool prime[1000005]={false};
                    // s[0]=0;
                    // s[1]=1;
                    // s.pb(1);
                    // t.insert(1);
                    for (int p=2; p<=n; p++) 
                    { 
                        
                    if(prime[p]==false)
                    {
                        for(ll j=p+p;j<=1000005;j+=p)
                        {
                            prime[j]=true;
                        }    
                    }
                    } 
                    for(ll i=2;i<1000005;i++)
                    {
                        if(!prime[i])
                        {
                            // s.pb(i);
                            s1.insert(i);
                        }
                    }
                } 
                void eea(ll a, ll b, ll & x, ll & y) {
                if (a == 0) {
                    x = 0;
                    y = 1;
                    return ;
                }
                ll x1, y1;
                eea(b % a, a, x1, y1);
                x = y1 - (b / a) * x1;
                y = x1;
                return ;
            }
            ll modinverse(ll a,ll m)
            {
                ll x, y;
                eea(a, m, x, y);
                if (__gcd(a,m) != 1) {
                return -1;
                }
            else {
                x = (x % m + m) % m;
                cout << x << endl;
                return x;
            }
            }
                ll fact[1000007]={0};
                ll expo(ll x, ll y) {ll res=1;x=x%MOD;while(y>0){if(y&1)res=(1ll*res*x)%MOD;
                y=y>>1;x=(1ll*x*x)%MOD;} return res;}
                void facto() {fact[0]=1;fact[1]=1;for(ll i=2;i<100007;i++)fact[i]=(fact[i-1]*i)%MOD;}
                ll npr(ll n,ll r) {facto(); ll res=1; res=fact[n]; res=(res*(expo(fact[n-r],MOD-2)))%MOD; return res; }
                ll ncr(ll n,ll r){ ll res=1; if(r>n-r)r=n-r; for(ll i=0;i<r;i++) {  res*=n-i;  res/=i+1; } return res;}
                    ll C(ll n, ll k) {
            ll res = 1;
            for (ll i = 1; i <= k; ++i)
                res = ((res) * (n - k + i) / i)%MOD;
            return (ll)(res + 0.01)%MOD;
        }
    int const N=1e6+5;
    int main()
    {
        fast
        // SieveOfEratosthenes();
    //    ct
            { 
                ll k,a,b;
                cin>>k>>a>>b;
                ll k1=a/k,k2=b/k;
                if(k2-k1>=1||a%k==0||b%k==0)
                {
                    cout<<"OK";
                }
                else
                {
                    {
                        cout<<"NG";
                    }
                }
                
                
            }   
    }
                

Measured memory_bytes: 3588