let n = Number(require('fs').readFileSync('/dev/stdin', 'utf8'))
const alphabetCounts = 26
const chars = new Array(alphabetCounts).fill().map((_, i) => String.fromCharCode(i + 97))
let current = 1
while (true) {
  const currentPow = Math.pow(alphabetCounts, current++)
  if (n <= currentPow) {
    let str = (n - 1).toString(26)
    while (str.length < current - 1) {
      str = '0' + str
    }
    console.log(Array.from(str).map(v => {
      const cc = v.charCodeAt(0)
      return String.fromCharCode(cc <= 57 ? cc + 49 : cc + 10)
    }).join(''))
    break
  }
  n -= currentPow
}