$p = 1 - ( factorial($n) * c(2**32, $n) / 365**$n )

##</code><code>##

  sub e () { 2.718281828 }
  my $t = ($n**2) / (2**33);
  $p = 1 - ( e ** -$t );

##</code><code>##

  $n = sqrt(20 * (2 ** 33));