#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

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

ll a;

double f(double x) {
  return x*log(a)/log(x);
}

int main() {

    cin >> a;
  
    double low = 0;
    double high = 1e18+7;

    int cnt = 500;
    while (cnt--) {
        double c1 = (low * 2 + high) / 3;
        double c2 = (low + high * 2) / 3;

        if (f(c1) > f(c2)) low = c1;
        else high = c2;
    }

    int l=low;
  ll b=a,c=a;
  int cnt1=0,cnt2=0;
    while(b>0){
      b/=l;
      cnt1++;
      }
      while(c>0){
        c/=(l+1);
        cnt2++;
      }
    if(a<6) cout<<a<<endl;
    else cout<<min(l*cnt1,(l+1)*cnt2)<< endl;

}