{
    local $SIG{__DIE__};
    local $@ = "";
                                                                   
    eval {
        local $SIG{ALRM} = sub { die("alarm\n") };

        alarm(3);
        chomp($input = <STDIN>); # potentially long operation
        alarm(0);

        1;
    } or do {
        die($@) unless $@ eq "alarm\n";
                                                                   
        # timed out
        warn("No answer for three seconds.\n");
        $input = "";
    }
}