"use strict";

function main(input) {
  const alphabet = "abcdefghijklmnopqrstuvwxyz";
  const alphabet_arr = alphabet.split("");
  input = input.trim();
  const az = 26;
  let num = parseInt(input);
  let n = 1; //桁数
  let m = 0;
  let ans = [];

  while (num > 26) {
    n++;
    const a = num % az;
    ans.push(a);
    num = Math.floor(num / az);
  }
  ans.push(num % az);
  for (let i in ans) {
    ans[i] = alphabet_arr[ans[i] - 1];
  }
  console.log(ans.reverse().join(""));
}
var f = function (a, b) {
  return a - b;
};

main(require("fs").readFileSync("/dev/stdin", "utf-8"));
