#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
using Pld = pair<ld, ld>;
using Vec = vector<ll>;
using VecP = vector<P>;
using VecB = vector<bool>;
using VecC = vector<char>;
using VecD = vector<ld>;
using VecS = vector<string>;
template <typename T>
using Vec2 = vector<vector<T>>;
#define REP(i, m, n) for(ll i = (m); i < (n); ++i)
#define REPN(i, m, n) for(ll i = (m); i <= (n); ++i)
#define REPR(i, m, n) for(ll i = (m)-1; i >= (n); --i)
#define REPNR(i, m, n) for(ll i = (m); i >= (n); --i)
#define rep(i, n) REP(i, 0, n)
#define repn(i, n) REPN(i, 1, n)
#define repr(i, n) REPR(i, n, 0)
#define repnr(i, n) REPNR(i, n, 1)
#define all(s) (s).begin(), (s).end()
#define pb push_back
#define fs first
#define sc second
template <typename T>
bool chmax(T &a, const T b){if(a < b){a = b; return true;} return false;}
template <typename T>
bool chmin(T &a, const T b){if(a > b){a = b; return true;} return false;}
template <typename T>
ll pow2(const T n){return (1LL << n);}
template <typename T>
void cosp(const T n){cout << n << ' ';}
void co(void){cout << '\n';}
template <typename T>
void co(const T n){cout << n << '\n';}
template <typename T1, typename T2>
void co(pair<T1, T2> p){cout << p.fs << ' ' << p.sc << '\n';}
template <typename T>
void co(const vector<T> &v){for(T i : v) cosp(i); co();}
template <typename T>
void co(initializer_list<T> v){for(T i : v) cosp(i); co();}
void ce(void){cerr << '\n';}
template <typename T>
void ce(const T n){cerr << n << '\n';}
template <typename T>
void cesp(const T n){cerr << n << ' ';}
template <typename T>
void ce(initializer_list<T> v){for(T i : v) cesp(i); ce();}
void sonic(){ios::sync_with_stdio(false); cin.tie(0);}
void setp(const ll n){cout << fixed << setprecision(n);}
constexpr int INF = 1e9+1;
constexpr ll LINF = 1e18L+1;
constexpr ll MOD = 1e9L+7;
constexpr ll MOD_N = 998244353;
constexpr ld EPS = 1e-11;
const double PI = acos(-1);

int main(void){
	ll a;
	cin >> a;

	ll ans = LINF;
	REPN(i, 2, a) {
		if(i >= 1e6)
			break;
		ll t = i, cnt = 1;
		while(t < a) {
			t *= i;
			cnt++;
		}
		chmin(ans, i * cnt);
	}
	co(ans);

	return 0;
}