#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979323846;

int main(){
    ll a;
    scanf("%lld",&a);
    ll ans=LINF;
    for(ll i=2;i<=min(a,1000000LL);i++){
        ll now=1;
        ll c=0;
        while(now<a){
            now*=i;
            ++c;
        }
        ans=min(ans,i*c);
    }
    printf("%lld\n",ans);
    return 0;
}