#include <bits/stdc++.h>
using namespace std;
const int INF = 1000000000;
int main() {
  int hy, ay, dy;
  int hm, am, dm;
  int ph, pa, pd;
  scanf("%d%d%d%d%d%d%d%d%d", &hy, &ay, &dy, &hm, &am, &dm, &ph, &pa, &pd);
  int ans = INF, least = 0;
  int cur_ay = ay;
  if (cur_ay < dm + 1) {
    least = pa * (dm + 1 - cur_ay);
    cur_ay = dm + 1;
  }
  int tar_ay, tar_dy;
  int c1, c2;
  for (int k = 1; k <= 100; k++) {
    c1 = least;
    tar_ay = dm + hm / k + (hm % k ? 1 : 0);
    if (tar_ay > cur_ay) c1 += (tar_ay - cur_ay) * pa;
    tar_dy = am - hy / k + (hy % k ? 0 : 1);
    if (tar_dy <= dy)
      ans = min(ans, c1);
    else {
      for (int j = 0; dy + j < tar_dy; j++) {
        c2 = c1 + j * pd + (k * (am - dy - j) - hy + 1) * ph;
        if (c2 < ans) ans = c2;
      }
      ans = min(c1 + (tar_dy - dy) * pd, ans);
    }
  }
  if (ans == INF) ans = 0;
  printf("%d\n", ans);
  return 0;
}
