#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<utility>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<functional>
#include<math.h>
#include<random>
#include <bitset>
#include <cassert>
#include <complex>
using namespace std;
#define N (1000000000+7)
//#define N 998244353
#define INF 1e16
typedef long long ll;
typedef pair<int,int> P;
const int inf = 1e8;


int main() {
    ll A;
    cin>>A;
    ll ans = A;
    for(ll i=2;i*i<=A;i++){
        ll t = 1;
        ll num = 0;
        while(t<A){
            t*=i;
            num++;
        }
        ans = min(ans,num*i);
    }
    cout<<ans<<endl;
}