#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
using namespace std;
using i32 = int_fast32_t;
using i64 = int_fast64_t;
#define rep(i, n) for (i32 i = 0; i < (i32)(n); i++)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
using P = pair<i64,i64>;

int main(){
ios::sync_with_stdio(false);
std::cin.tie(nullptr);
i64 n;
cin >> n;
i64 ans = 1e18;
for(i32 i = 2; i < 100; i++){
    i64 cnt = 0;
    i64 base = 1;
    while(1){
        if(base >= n)break;
        base *= i;
        cnt++;
    }
    if(cnt != 0)
    ans = min(ans,i * cnt);
}
cout << ans << endl;
}