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);
//   do {
//     const value = Math.pow(26, k);

//     if (value + sum >= n) {
//       const baseNum = n - sum;
//       result = convert(baseNum);
//       break;
//     } else {
//       sum += value;
//       k++;
//     }
//   } while (n > sum);
//   if (!result) {
//     throw new Error("program error");
//   }

  return result;
};

const convert = (value) => {
  let result = "";
  do {
    const numbers = calculate(value);
    value = numbers.div;
    result = convertNumToChar(numbers.per) + result;
  } while (value !== 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) => {
  return String.fromCharCode(CHAR_CODE_0F_a + num - 1);
};
