#include <iostream>
#include <vector>

#define rep(i, n) for (int i = 0; i < (n); ++i)
typedef long long ll;
using namespace std;

int main(int, char const *[])
{
  int n, a,b,c;
  int ans = 0;
  cin >> n>>a>>b>>c;
  ans=n/10*c+(n%10)/5*b+(n%5)/3*a;
  cout << ans << endl;
  return 0;
}

// vim: set ts=2 sw=2 sts=2: