hdf

import sys
from decimal import Decimal, getcontext

k = int(sys.argv[1]) if len(sys.argv) > 1 else 70

def bellard(n):
  getcontext().prec = n + 1
  return Decimal(1.0/(2**6)) * sum([Decimal(-1)**k/(1024**k) * (Decimal(256)/(10*k+1) + Decimal(1)/(10*k+9) - Decimal(64)/(10*k+3) - Decimal(32)/(4*k+1) - Decimal(4)/(10*k+5) - Decimal(4)/(10*k+7) - Decimal(1)/(4*k+3)) for k in range(n)])

print(bellard(k))