#!/usr/bin/env python

# Written by Jason Jung <jrjung@gmail.com>
# Last modified: 2006.10.04
# This is a simple script that uses the formula
# pi = 16 * arctan(5, y) - 4 * arctan(239, y)
# to calculate the value of Pi to any number of digits

# The formulas for Pi were supplied by works of
# Carey Bloodworth and the users of Wikipedia

# USAGE: ./machin.py <number of digits to calculate>

# TEST RUN TIME
#    real    1388m51.658s
#    user    1223m32.380s
#    sys     120m20.907s
# OS: Linux 2.6.15-26-386/i686
# CPU: mobile AMD Athlon(tm) 4 Processor (500.095 MHz)


def arctan(x, y):
  sum = xpow = y // x
  z = 3
  sign = -1
  while 1:
    xpow = xpow // (x * x)
    term = xpow // z
    if not term:
      break
    sum += sign * term
    sign = -sign
    z += 2
  return sum

def pi(n):
  y = 10**(n + 10)
  pi = 16 * arctan(5, y) - 4 * arctan(239, y)
  return pi // 10**10

if __name__ == '__main__':

  from sys import argv
  print pi(int(argv[1]))