#include <bits/stdc++.h>
using namespace std;

int main(){
    long long n, ans;
    cin >> n;
    ans = n;
    for(long long i = 1; i * i <= n; i++){
        if(n % i == 0){
            if(i >= 3)ans = min(ans, i);
            if(n / i >= 3)ans = min(ans, n / i);
        }
    }
    cout << ans << endl;
}