#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, j;
  cin >> n;
  set<int> row;
  set<int> col;
  map<int, int> row_map;
  map<int, int> col_map;
  for (i = 1; i <= n; i++) {
    string s;
    cin >> s;
    for (j = 1; j <= n; j++) {
      if (s[j - 1] == '.') {
        row.insert(i);
        col.insert(j);
        row_map[i] = j;
        col_map[j] = i;
      }
    }
  }
  if (row.size() == n) {
    for (i = 1; i <= n; i++) {
      cout << i << " " << row_map[i] << endl;
    }
  } else if (col.size() == n) {
    for (j = 1; j <= n; j++) {
      cout << col_map[j] << " " << j << endl;
    }
  } else
    cout << -1 << endl;
}
