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


#open(FH,"$ARGV[0]") or die;
#my @temp=<FH>;
#close FH;
my @temp = <DATA>;

my $mean = Mean (\@temp);
my $variance = variance(\@temp);
print "$variance\n";

sub sum {
    my ($arrayref) = @_;
    my $result;
    foreach(@$arrayref) { $result+= $_; }
    return $result;
}

sub Mean {
    my ($arrayref) = @_;
    my $result;
    foreach (@$arrayref) { $result += $_ }
    return $result / @$arrayref;
}


sub variance {
    my ($arrayref)= @_;
    my @a = map ( ($_ - $mean)**2, @$arrayref);
    return sum(\@a) / scalar @$arrayref;
}

__DATA__
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