import strutils, sequtils
let c = stdin.readLine.split

proc tryX(x: int): string =
  result = ""
  var arr = newSeqWith(0, 0)
  for c in c:
    arr.add c.replace("?", $x).parseInt
  let m = arr[1]
  if arr == arr.deduplicate:
    if m == arr.max or m == arr.min:
      result = $x

var ans = ""
ans.add (1).tryX
ans.add (4).tryX
echo ans