import math
term = 1
sum = 1103
k = 1
while term > 1e-15:
   frac0 = 1
   frac4 = 1
   for i in range (k):
      frac0 *= (i+1)
   for j in range (4*k):
      frac4 *= (j+1)
   term = (frac4*(1103+26390*k))/((frac0**4)*(396**(4*k)))
   sum += term
   k+=1
p = 1/(2*math.sqrt(2)*sum/9801)
print (p)