$ perl -Mstrict -Mwarnings -E '
    my $numone;
    my $numtwo;
    print "Please enter first number ";
    $numone = <STDIN>;
    print "Please enter second number ";
    $numtwo = <STDIN>;

    #if ($numone < $numtwo); { <--- WRONG: no semicolon here
    if ($numone < $numtwo) {
        print $numone;
        print $numtwo;
    }
    # elsif { <--- WRONG: should be else
    else {
        print $numtwo;
        print $numone;
    }

    print "Hit enter when done: "; <>;
'
Please enter first number 456
Please enter second number 123
123
456
Hit enter when done: