#pragma GCC optimize("Ofast", "unroll-loops", "omit-frame-pointer","inline")
#pragma GCC option("arch=native","tune=native","no-zero-upper")
#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;

#define X first
#define Y second


const ll mod = 1000000007;
//const ll mod = 998244353;



ll pew(ll a, ll b) {
    ll res = 1;
    while (b>0) {
        if (b&1) res = res*a%mod;
        b >>= 1;
        a = a*a%mod;
    }
    return res;
}



void solve() {
    ll n;
    cin >> n;
    for (ll i=2;i<=10000;i++) {
        ll ok = 1;
        for (ll j=2;j*j<=i;j++) {
            if (i%j==0) {
                ok = 0;
                break;
            }
        }
        if (ok==0) continue;
        if (n%i==0) continue;
        cout << i << "\n";
        return;
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    int T = 1;
    //cin >> T;
    while (T--) solve();
    return 0;
}