#include<iostream>
#include<stdio.h>
#include<vector>
#include<algorithm>
#include<set>
#include<string>
#include<map>
#include<string.h>
#include<complex>
#include<math.h>
#include<queue>
#include <functional>
#include<time.h>
#include<iomanip>
#include<cassert>
#include<bitset>
#include<sstream>
#include<list>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
int main() {
	long n;
	cin >> n;
	long m = 100000000000000;
	for (long i = 2; i <= 1000000; i++) {
		long x = i;
		long cnt = 1;
		while (x < n&& x>0) {
			cnt++;
			x *= i;
		}
		m = min(cnt * i, m);
	}
	cout << m << endl;
	return 0;
}