#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  ll n;
  cin >> n;
  ++n;
  string ans;
  while (n > 0) {
    --n;
    ans += 'A' + n % 26;
    n /= 26;
  }
  reverse(ans.begin(), ans.end());
  cout << ans << '\n';
  return 0;
}