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

using namespace std;
using LL = long long;
using P = pair<int,int>;
const LL INF = 1e15;

int main(){
	LL A;
	cin >> A;
	LL ans=INF;
	for(LL i=2; i<=100; i++){
		LL res=1, num=i;
		while(num<A){
			res++;
			num*=i;
		}
		ans=min(ans,res*i);
	}
	cout << ans << endl;

	return 0;
}