#include <fstream>

using namespace std;
ifstream cin("taxe.in");
ofstream cout("taxe.out");
static int bruh(int x){
    int sum=0;
    while(x>0) {
    sum+=x*4;
    x/=4;
  }
  return sum;
}
int main()
{
    int n,st,dr,mid;
    cin>>n;
    st=0;
    dr=n;
    while(dr>st+1)
    {
        mid=(st+dr)/2;
        if(bruh(mid)<n) st=mid;
        else dr=mid;
    }
    cout<<dr;
    return 0;
}