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

my %data;
while ( <DATA> ) {
    chomp;
    my ($stamp, $reading) = split;
    next if ! $stamp || ! defined $reading;
    $data{$stamp}{COUNT}++;
    $data{$stamp}{MAX} = $reading if ! defined $data{$stamp}{MAX} || $reading > $data{$stamp}{MAX};
    $data{$stamp}{MIN} = $reading if ! defined $data{$stamp}{MIN} || $reading < $data{$stamp}{MIN};
    $data{$stamp}{SUM} += $reading;
}
print join "\t" , "TIMESTAMP", "MAX", "MIN", "AVG";
print "\n";
for my $stamp ( sort keys %data ) {
    print join "\t", $stamp, @{$data{$stamp}}{ qw(MAX MIN) }, $data{$stamp}{SUM} / $data{$stamp}{COUNT};
    print "\n";
}