#include <iostream>
using namespace std;

int udiv(int g, int v) {return g < 0? 0 : (g + v - 1) / v;}

int main() {
  int np, nm, n0, r;
  while (cin >> np >> nm >> n0 >> r) {
    if (np == 0 && nm == 0 && n0 == 0 && r == 0) return 0;

    int result = 10000000;
    for (int i = 0; i <= 100; i++)
      result <?= n0 * udiv(100, r) +
	nm * (i+udiv(100 - (r-1)*i, r)) + 
	np * (i+udiv(100 - (r+2)*i, r));
    
    cout << result << endl;
  }
}