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

print "Enter how many iterations:\n";
chomp(my $i = <>);

my $x = $i - 1;
my $y = sqrt(2);
do { $y = sqrt(2 + $y) while (--$x);
     $y = sqrt(2 - $y);
   } if $x;

my $z = $y * (2 ** $i);

print "Pi is close to: $z\n";