#include <iostream>
#include <fstream>
using namespace std;
int main()
{
setlocale(LC_ALL , "Russian");
int N;
cout << "Введите N";
cin >> N;
ofstream file("proga.txt");
for (int i = 0; i < N; i++)
{
for (char j = 'A'; j <= 'A' + i; j++)
file << j;
file << '\n';
}
file.close();
return 0;
}