function mod (number, divisor) {
  let result = 0

  for (let i = 0; i < number.length; i++) {
    result = (result * 10 + +number[i] - '0') % divisor
  }

  return result
}

function divide (number, divisor) {
  let ans = ''
  let index = 0
  let temp = +number[index]

  while (temp < divisor) {
    temp = temp * 10 + +number[++index]
  }

  index++
  while (number.length >= index) {
    ans += ~~(temp / divisor)
    temp = (temp % divisor) * 10 + +number[index++]
  }

  return ans || '0'
}

let digits = []

for (let i = 65; i <= 90; i++) {
  digits.push(String.fromCharCode(i))
}

for (let i = 97; i <= 122; i++) {
  for (let j = 65; j <= 90; j++) {
    digits.push(String.fromCharCode(i) + String.fromCharCode(j))
  }
}

let n = gets()
let result = []

do {
  result.unshift(digits[mod(n, 256)])
  n = divide(n, 256)
} while (n !== '0')

print(result.join(''))