my %h = (
    '500x500'   => 505544,
    '750x750'   => 1118012,
    '1000x1000' => 1986284,
    '1500x1500' => 4468241,
    '2000x2000' => 7907740,
);

my $pixel = '1000x1000';
my $url_file = 'http://speedserver/file'.$pixel.'.jpg';
my $file = 'file'.$pixel.'.jpg';

unlink $file or die $! if -e $file;