#!/usr/bin/perl
use strict;
use warnings;

my %hash = ();

while (my $line = <DATA>){
  chomp $line;
  my ($k, $v) = split / /, $line;
  $hash{$k} = $v;
}

my @keys_sorted = sort{ $hash{$b} <=> $hash{$a} }keys %hash;

for my $key ( @keys_sorted ){
  print "$key -> $hash{$key}\n";
}

__DATA__
woche1 4
woche2 3
woche3 1
woche4 7
woche5 2