#include <bits/stdc++.h>
#define rep(i,n) for(int i=(0);i<(n);i++)

using namespace std;

typedef long long ll;

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

// condを満たす最小のxを求める(lower_bound)
// 全てのxが条件を満たさない場合はnを返す(nはとりえない値)

ll INF = 1e18 + 1e17;
double eps = 1e-10;

bool cond(ll t, ll y, ll a){
	double ret = 1.0;
	rep(i, y) ret *= (double) t;
	return (double) a < ret + eps;
}

ll lower_bound_cond(ll y, ll a){
	ll lb = 2, ub = INF;

	while(ub - lb > 1){
		ll mid = (lb + ub) / 2;

		bool ok = cond(mid, y, a);
		// cout << y << "," << mid << "," << ok << endl;
		if(ok) ub = mid;   // Answer is in (lb, mid]
		else lb = mid;            // Answer is in (mid, ub]
	}

	// now lb + 1 = ub
	return ub;
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	ll a;
	cin >> a;

	ll ans = INF;

	// for(ll y = 1; y <= 62; y++){
	for(ll y = 1; y <= 62; y++){
		ll x = lower_bound_cond(y, a);
		chmin(ans, x * y);
	}

	cout << ans << endl;
}