#include <bits/stdc++.h>
using namespace std;
int main() {
  long long t, n, m, k, rem, each, x, y, i, j, ans;
  cin >> t;
  while (t--) {
    cin >> n >> m >> x >> y;
    string s[n];
    long long one = 0, two = 0;
    for (i = 0; i < n; i++) {
      cin >> s[i];
    }
    for (i = 0; i < n; i++) {
      for (j = 0; j < m; j++) {
        if (s[i][j] == '.') one++;
        if (j == 0) continue;
        if (s[i][j] == '.' && s[i][j - 1] == '.') {
          two++;
          s[i][j] = '$';
          s[i][j - 1] = '$';
        }
      }
    }
    long long p1, p2;
    p1 = x * one;
    p2 = y * two + x * (one - two * 2);
    ans = min(p1, p2);
    cout << ans << endl;
  }
}
