#include <bits/stdc++.h> using namespace std; int main() { int n; cin>>n; char a = 'A'; string s1 = ""; for(int i = 0;i < n;i++) { string s2 = s1; s1 = s2 + a + s2; int e = int(a) + 1; a = e; } cout<<s1; return 0; }