#include <bits/stdc++.h>
using namespace std;
using lli = long long int;
using ld = long double;
using ulli = unsigned long long int;
void debug() { cerr << endl; }
template <class T>
T gcd(T a, T b) {
  return (b != 0 ? gcd<T>(b, a % b) : a);
}
template <class T>
T lcm(T a, T b) {
  return (a / gcd<T>(a, b) * b);
}
template <typename T, typename... hello>
void debug(T arg, const hello &...rest) {
  cerr << arg << ' ';
  debug(rest...);
}
const lli maxN = 20000;
string get_res(lli n) {
  char str[maxN];
  lli i = 0;
  while (n > 0) {
    lli rem = n % 26;
    if (rem == 0) {
      str[i++] -= 'z';
      n = (n / 26) - 1;
    } else {
      str[i++] = (rem - 1) + 'a';
      n /= 26;
    }
  }
  str[i] = '\0';
  reverse(str, str + strlen(str));
  return str;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  lli n;
  cin >> n;
  cout << get_res(n);
}
