#include <bits/stdc++.h>   using namespace std;   int n, f = -1;   int main() {     cin >> n;     cout << (n * n + 1) / 2;     for (int i = 0; i < n; i++) {       f = f * (-1);       cout << endl;       for (int j = 0; j < n; j += 2) {         if (f == 1) {           if (j != n - 1)             cout <<  C. ;           else             cout <<  C ;         } else {           if (j != n - 1)             cout <<  .C ;           else             cout <<  . ;         }       }     }     return 0;   }   