#!/usr/bin/env tclsh8.6

gets stdin line
set crabs [lsort -integer [split $line ,]]

proc triangle {n} {
  expr {$n * ($n+1) / 2}
}

set minfuel 99999999
for {set pos [lindex $crabs 0]} {$pos <= [lindex $crabs end]} {incr pos} {
  set fuel 0
  foreach c $crabs {
    incr fuel [triangle [expr {abs($pos - $c)}]]
  }
  if {$fuel < $minfuel} {set minfuel $fuel}
}

puts $minfuel