#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;
use Term::ReadKey;

my $count = 0;
my $char = undef;

ReadMode('cbreak');

while (!defined $char) {
    $char = ReadKey(-1);
    $count++;
}

print "$count\n";

# Put the terminal back the way you found it.
END {
    ReadMode('restore');
}