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

ll N,i;

int hantei(ll i){
  if(N/i==N/(i+1)){
    return 1;
  }
  else{
    return 0;
  }
}

int main(){
  cin>>N;
  ll l=1;
  ll r=N;
  ll m;
  while(r > l+1){
    m=(l+r)/2;
    if(hantei(m)==1){
      r=m; 
    }
    else{
      l=m;
    }
  }
  if(m==0){
    cout<<2<<endl;
    return 0;
  }
  //cout<<N/m<<" "<<m<<endl;
  cout<<N/m+m-1<<endl;
}