#include <bits/stdc++.h>
using namespace std;

int main(){
    int64_t A;
    cin >> A;

    int64_t ans = 1e18;

    auto enough = [](int64_t M, int N, int64_t A){
        __int128_t P = 1;
        while(N--){
            P *= M;
            if(P >= A) return true;
        }
        return false;
    };

    for(int N=1; N<=60; N++){
        int64_t ok = A, ng = 0;
        while(ok-ng>1){
            int64_t mid = (ok+ng)/2;
            (enough(mid, N, A) ? ok : ng) = mid;
        }
        ans = min(ans, N*ok);
    }

    cout << ans << endl;
    return 0;
}