#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  cin >> N;
  string s = "abcdefghijklmnopqrstuvwxyz";
  string t;
  for (int i = 0; i < N; i++) {
    t = s.at(i);
  }
  cout << t << endl;
}
