C++ :

#include<iostream>
using namespace std;
int main() {
	int a, b = 1;
	cin >> a;
	for (int i = a-1; i >= 0; i--) {
		for (int j = 1; j <= a - i; j++) {
			if (a == 7 && b == 27) {
				cout << "AB";
				break;
			}
			cout << char(b + 64);
			b++;

		}
		cout << endl;
	}
}