#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; ++i)
#define rep2(i, x, n) for(ll i = x, i##_len = (n); i < i##_len; ++i)
#define all(n) begin(n), end(n)
using ll = long long;
using P = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vs = vector<string>;
using vc = vector<char>;
using vb = vector<bool>;
using vd = vector<double>;
vi dir = {-1, 0, 1, 0, -1, -1, 1, 1, -1};

int main() {
  ll a;
  cin >> a;
  ll ans = 1e18;
  rep2(i, 2, 1e5 + 1) {
    ll k = i, n = 1;
    while(k < a) {
      n++;
      if(k < a / i)
        k *= i;
      else
        break;
    }
    ans = min(ans, i * n);
  }
  cout << ans << endl;
}