text: #include <iostream>
  using namespace std;
  
  //P13903
  //pre: natural n >= 1.
  //post: tauler n x n. 
  
  int main () {
  	int n;
  	cin >> n;
  	for (int i = 0; i < n; ++i) {
  		for (int j = 0; j < n; ++j) {
  			if ((i+j)%2 == 0) {
  				cout << '.';
  			} else {
  				cout << '*';
  			}
  		}
  		cout << endl;
  	}
  	return 0;
  }
  