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