proc getchar_unlocked():char {. importc:"getchar_unlocked",header: "<stdio.h>" .}
proc scan(): int =
  while true:
    var k = getchar_unlocked()
    if k < '0': break
    result = 10 * result + k.ord - '0'.ord
proc putchar_unlocked(c:char){. importc:"putchar_unlocked",header: "<stdio.h>" .}
proc printAscii(a:int) =
  if a == 0:
    putchar_unlocked('A')
    return
  template div26(a:int) : int = a div 26
  template mod26(a:int) : int = a mod 26
  var n = a
  var rev = a
  var cnt = 0
  while rev.mod26 == 0:
    cnt += 1
    rev = rev.div26
  rev = 0
  while n != 0:
    rev = rev * 26 + n.mod26
    n = n.div26
  while rev != 0:
    putchar_unlocked((rev.mod26 + 'A'.ord).chr)
    rev = rev.div26
  while cnt != 0:
    putchar_unlocked('A')
    cnt -= 1
# 0 1 2 3 10 11 12 13 20 21 22 23
# A G H Z BA BB ..

scan().printAscii()
putchar_unlocked('\n')