#include<iostream>
#include<vector>
#include<string>
#include<cmath>
using namespace std;

int main()  {
    int m,n=0,k=0;
    cin>>m;
    k=m;
    while(m>=2){
       n=m/2;
       k=n+k;
       m=n+(m-2*(m/2));
    }cout<<k;
    return 0;
}