#include <iostream>
using namespace std;
int main(){
  long long n;cin>>n;
  long long mn = 0;
  long long mx = 1000000000;
  while(mx-mn > 1){
    long long ce = (mn+mx)/2;
    if(ce*ce < n)mn = ce;
    else mx = ce;
  }
  if(mx*mx == n){
    cout << mx*2-1 << endl;
  }else{
    cout << (mx-1)*2 << endl;
  }
}