from numpy import random
from math import sqrt

L=input('Enter L: ') #in cm

NumberOfFissions=1
PositionOnLine=L*random.random()
print PositionOnLine
R=sqrt(71.4) #in cm

#number of fissions produced in fission is 2
#distance to next fission R=sqrt(71.4)

for i in range(1,101):
    if NumberOfFissions!=0:
        for e in range(1,NumberOfFissions+1):
            Decider=random.random()
            if Decider>0.5: #moves neutron right
                PositionOnLine+=R #if in 0 to L, fission occurs
                if PositionOnLine<=L or PositionOnLine>=0:
                    NumberOfFissions+=1
                if PositionOnLine>L or PositionOnLine<0: #if not in 0 to L, neutron escapes
                    NumberOfFissions-=1
            if Decider<=0.5: #moves neutron left
                PositionOnLine-=R
                if PositionOnLine<=L or PositionOnLine>=0:
                    NumberOfFissions+=1
                if PositionOnLine>L or PositionOnLine<0:
                    NumberOfFissions-=1
print NumberOfFissions