#include <iostream>
#include <vector>

using std::vector;

bool Bit(int mask, int pos) {
  return ((mask >> pos) & 1);
}

int main() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(0);
  std::cout.tie(0);
  int n;
  std::cin >> n;
  vector<vector<bool>> can_work_together(n, vector<bool>(n));
  for (int i = 0; i < n; ++i) {
    std::string str;
    std::cin >> str;
    for (int j = 0; j < n; ++j) {
      can_work_together[i][j] = (str[j] == 'Y');
    }
  }
  vector<bool> dp(1 << n, false);
  dp[0] = true;
  for (int mask = 1; mask < (1 << n); ++mask) {
    for (int pos = 0; pos < n; ++pos) {
      if (Bit(mask, pos)) {
        for (int neighbour = 0; neighbour < n; ++neighbour) {
          if (can_work_together[pos][neighbour] and Bit(mask, neighbour)
            and dp[mask xor ((1 << pos) | (1 << neighbour))]) {
            dp[mask] = true;
          }
        }
      }
    }
  }
  int max_cnt_of_one = 0;
  for (int mask = 0; mask < (1 << n); ++mask) {
    int temp_cnt_of_one = 0;
    if (dp[mask]) {
      for (int i = 0; i < n; ++i) {
        if (Bit(mask, i)) {
          ++temp_cnt_of_one;
        }
      }
      max_cnt_of_one = std::max(max_cnt_of_one, temp_cnt_of_one);
    }
  }
  std::cout << max_cnt_of_one << std::endl;
}