#include <iostream>
#include <algorithm>
#include <vector>

int main( ) {
   std::ios_base::sync_with_stdio(0);
   std::cin.tie(0);
   std::cout.tie(0);

   int n;
   std::cin >> n;

   std::vector<int> pos[n];
   char mapa[n][n];
   for (int i = 0; i < n; ++i) {
      for (int j = 0; j < n; ++j) {
         std::cin >> mapa[i][j];
         if (mapa[i][j] == '*') {
            pos[i].push_back(j);
         }
      }
   }

   int costo[n + 1][n] = { };
   for (int i = n - 1; i >= 0; --i) {

      for (int j = 0; j < n; ++j) {
         if (mapa[i][j] != '#') {
            costo[i][j] += costo[i + 1][j];
         }
      }

      for (auto it : pos[i]) {
         int ini = it, fin = it + 1;
         for (; ini >= 0 && mapa[i][ini] != '#'; --ini) {
            costo[i][ini] += 1;
         }
         for (; fin < n && mapa[i][fin] != '#'; ++fin) {
            costo[i][fin] += 1;
         }
         int max = std::max_element(costo[i][ini], costo[i][fin]);
         for (int a = ini; a <= fin; ++a) {
            costo[i][a] = max;
         }
      }
   }
   std::cout << costo[0][0] << "\n";
}