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