#!/usr/bin/env tclsh

# From rosettacode
proc ::tcl::mathfunc::mulinv {a b} {
  if {$b == 1} {return 1}
  set b0 $b; set x0 0; set x1 1
  while {$a > 1} {
    set x0 [expr {$x1 - ($a/$b) * [set x1 $x0]}]
    set b [expr {$a % [set a $b]}]
  }
  incr x1 [expr {($x1 < 0) * $b0}]
}

proc chineseRemainder {nList aList} {
  set sum 0; set prod [::tcl::mathop::* {*}$nList]
  foreach n $nList a $aList {
    set p [expr {$prod / $n}]
    incr sum [expr {$a * mulinv($p,$n) * $p}]
  }
  expr {$sum % $prod}
}

#puts [chineseRemainder {3 5 7} {2 3 2}]
#puts [chineseRemainder {17 13 19} {0 11 16}]
#puts [chineseRemainder {67 7 59 61} {0 6 57 58}]
#puts [chineseRemainder {67 7 59 61} {0 5 56 57}]

set time -1
foreach id [split [read stdin] ,] {
  incr time
  if {$id eq "x"} continue
  lappend nlist $id
  lappend alist [expr {($id - $time) % $id}]
}
puts [chineseRemainder $nlist $alist]