const main = input => {
  // 26進数
  const out = input % 26;
  if (input - out <= 0) {
    return array[out];
  }
  if ((input - out)/ 26 > 26) {
    return main((input - out) / 26) + array[out];
  } else {
    return array[(input - out) / 26] + array[out];
  }
}

array = '0 a b c d e f g h i j k l m n o p q r s t u v w x y z'.split(' ');
console.log(main(require("fs").readFileSync("/dev/stdin", "utf8")));
