#include <bits/stdc++.h>
#include <chrono>
using namespace std;
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()
#define fi first
#define se second
typedef long long ll;
typedef vector<ll> vec;
typedef vector<vec> mat;

ll N,M,H,W,Q,K,A,B;
string S;
typedef pair<ll, ll> P;
const ll INF = (1LL<<58);

template<class T> bool chmin(T &a, const T &b){
    if(a > b) {a = b; return true;}
    else return false;
}
template<class T> bool chmax(T &a, const T &b){
    if(a < b) {a = b; return true;}
    else return false;
}

int main() {
    cin>>N;
    ll ans = INF;
    reps(i, 2, 63){
        ll temp = 1, num = 1;
        while(N / i >= temp){
            temp *= i;
            num++;
        }
        //if(i < 10) cout<<i<<' '<<num<<endl;
        chmin(ans, num * i);
    }
    cout<<ans<<endl;
}