画正方形

#include<bits/stdc++.h>
using namespace std ;
char a = 'A' , b = 'A' ;
int main(){
	int n ;
	cin >> n ;
	for ( int i = 1 ; i <= n ; i++ ){
		a = b ;
		for ( int j = 1 ; j <= n ; j++ ){
			if ( j == 1 )	cout << char( ( a - 'A' ) % 26 + 'A' ) ;
			else	cout <<  char( ( ++a - 'A' ) % 26 + 'A' ) ;
		}
		cout << endl ;
		b++ ;
	}
    return 0 ;
}