#!/usr/bin/perl -w
use strict;
use Time::Local;

while (1) {
    print "Enter year (yyyy) and month (mm), separated by a space:";
    chomp(my $input = <STDIN>);
    last if !$input;

    my ($year, $month) = split / /, $input;
    my $dayname = (qw(Sun Mon Tue Wed Thu Fri Sat))[(gmtime(timegm(0,0,0,1,$month % 12,$year + $month / 12)-1))[6]];

    print "The last day of $month/$year will be a $dayname\n";
}