#include <iostream>

using namespace std;

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

    int best = 1000000000;
    for (int doits = 0; doits < 40; doits++){
      int np_units_left = 100 - min (100, (r+2) * doits);
      int nn_units_left = 100 - min (100, (r-1) * doits);

      int time = 
	n0 * ((100+r-1)/r) + 
	np * (doits + (np_units_left+r-1)/r) +
	nn * (doits + (nn_units_left+r-1)/r);
      
      best = min (best, time);
    }

    cout << best << endl;
  }
}