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

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 $m= $month % 12 + 1;
	my $y= $year+int($month/12);
	if ( $m<3) {
		$m+=12;
		--$y;
	}
	++$m;
    my $dayname = (qw(Sat Sun Mon Tue Wed Thu Fri))[(int($m * 30.6) + int($y * 365.25)-int($y / 100)+int($y / 400)) % 7];

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