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

// コンテスト中のみ
//#define int long long

#define ll long long
#define rep(i,n) for(int i = 0; i < (n); i++)
#define P pair<ll,ll>
#define ld long double
ll INF = (1LL << 60);
int MOD = 1000000007;



signed main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	ll a; cin >> a;
	ll ans = INF;
	for (ll i = 2; i <= 10010; i++) {
		ll cnt = 0;
		ll now = 1;
		while (true) {
			if (now >= (a + i - 1) / i) {
				break;
			}
			cnt++;
			now *= i;
		}
		ans = min(ans, i * (cnt+1));


	}
	cout << ans << endl;
	return 0;
}