process.stdin.resume();
process.stdin.setEncoding("utf8");
process.stdin.on("data", (input) => {
  const n = Number(input);

  const result = getResult(n);

  console.log(result);
});

const getResult = (n) => {
  let k = 1;
  let sum = 0;
  let result = convert(n);
  return result;
};

const convert = (value) => {
  let result = "";
  let div = value;
  let per = 0;
  do {
    const numbers = calculate(div);
    per = numbers.per;

    div = per === 0 ? numbers.div - 1 : numbers.div;
    result = convertNumToChar(per) + result;
  } while (div !== 0);
  return result;
};

const calculate = (num) => {
  const div = Math.floor(num / 26);
  const per = num % 26;
  return {
    div: div,
    per: per,
  };
};

const CHAR_CODE_0F_a = 97;

const convertNumToChar = (num) => {
  const offset = num > 0 ? num - 1 : 25;
  return String.fromCharCode(CHAR_CODE_0F_a + offset);
};
