#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  char input[n + 5][n + 5];
  for (int i = 0; i < n; i++) scanf("%s", input[i]);
  int row[n], col[n], count_row = 0, count_col = 0;
  for (int i = 0; i < n; i++) row[i] = -1;
  for (int j = 0; j < n; j++) col[j] = -1;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      if (input[i][j] == '.') {
        row[i] = j;
        col[j] = i;
      }
    }
  for (int i = 0; i < n; i++) {
    if (row[i] != -1) count_row++;
    if (col[i] != -1) count_col++;
  }
  if (count_row != n && count_col != n)
    printf("-1\n");
  else if (count_row == n) {
    for (int i = 0; i < n; i++) printf("%d %d\n", i + 1, row[i] + 1);
  } else
    for (int j = 0; j < n; j++) printf("%d %d\n", col[j] + 1, j + 1);
}
