#!/usr/bin/env tclsh9.0
namespace import ::tcl::mathop::*

proc defrag {line} {
    set disk [list]
    set state 0
    set id 0
    set block 0

    foreach c [split $line ""] {
        if {! [string is digit $c]} continue
        switch -- $state {
            0 {
                for {set i 0} {$i < $c} {incr i} {
                    lappend disk $id
                    incr block
                }
                if {$c != 0} {incr id}
                set state 1
            }
            1 {
                for {set i 0} {$i < $c} {incr i} {
                    lappend disk -1
                    lappend free $block
                    incr block
                }
                set state 0
            }
        }
    }

    set last [- [llength $disk] 1]
    while {[llength $free]} {
        # if {$last <= 50135} {
        #     puts "Loop, last=$last free=[lrange $free 0 9]"
        #     puts "Disk starting 50120: [lrange $disk 50120 50140]"
        # }

        # Abort if there are no more file blocks to move.
        if {[lindex $free 0] >= $last} break

        # Find last file block.
        while {[lindex $disk $last] < 0} {
            incr last -1
        }

        # Abort if it's already in place.
        if {[lindex $free 0] >= $last} break

        # Move it to the first free spot.
        set j [lindex $free 0]
        lset disk $j [lindex $disk $last]
        lset disk $last -1
        incr last -1
        set free [lrange $free 1 end]
        # puts "[join $disk ""] last=$last free=$free"
    }

    # puts "After defrag, last=$last free=[lrange $free 0 9] ..."
    # puts "Disk = [lrange $disk 0 19] ..."
    # puts "Disk starting 50120: [lrange $disk 50120 50140]"
    return $disk
}

proc checksum {disk} {
    set i 0
    set sum 0
    while {[lindex $disk $i] >= 0} {
        incr sum [* [lindex $disk $i] $i]
        incr i
    }
    return $sum
}

set line [read stdin]
set disk [defrag $line]
puts [checksum $disk]

# 6349343813585 too low