#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	char s1='A',s2;
	cin>>n;
	for(int i=1;i<=n;i++){
		if('A'<=s2&&s2<='Z') s2=s1;
		else s1='A',s2=s1; 
		for(int j=1;j<=n;j++){
			if('A'<=s2&&s2<='Z') cout<<s2;
			else s2='A',cout<<s2;
			s2++;
		}
		s1++;
		cout<<endl;
	}
	return 0;
}

有什么问题吗为什么WA