#include <bits/stdc++.h>
#define pb push_back

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

int main()
{
    ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);

	int t = 1;
	cin >> t;
    while(t-->0)
    {
        ll n;
        cin >> n;

        for(int i=0; i<n; i++)
        {
            for(int j=0; j<n; j++)
            {
                if(i + j == n - 1) cout << "C";
                else cout << ".";
            }
            cout << "\n";
        }
    }
}