#!/usr/bin/perl
#
# Non-linear analysis from Hacking Exposed: Web Security
# p. 180-181
#
# Small modifications by Paco Hope <paco@cigital.com> to use the
# Math::BigInt module

use Math::BigInt;

@seq = ();
@x = @y = @z = ();

while( <> ) {
  chomp( $val = $_ );
  push( @seq, Math::BigInt->new($val) );
}

for( $i=3; $i < $#seq; $i++ ) {
  push(@x, $seq[i]   - $seq[$i-1]);
  push(@y, $seq[i-1] - $seq[$i-2]);
  push(@z, $seq[i-2] - $seq[$i-3]);
}
for( $i=0; $i < $#seq; $i++ ) {
  printf( "%s %s %s\n", $x[$i], $y[$i], $z[$i]);
}