Sex ratio calculation

sexratio.py

from random import random

CONST_FAMILIES = 65536
CONST_GENERATIONS = 100
CONST_NATURAL_RATIO = 0.5

# User input data
A1 = input('How many families are there? (default ' + str(CONST_FAMILIES) + ')')
A2 = input('How many children will one family have? (default ' + str(CONST_GENERATIONS) + ')')

# Data processing
try:
 families = int(A1)
except:
 families = CONST_FAMILIES
try:
 generations = int(A2)
except:
 generations = CONST_GENERATIONS

# Total number of boys and girls
totalboys = 0
totalgirls = 0

# Loop
for i in range(0, generations):

 # Number of boys in current generations
 boys = 0
 for j in range(0, families):
  childsex = int(random() + CONST_NATURAL_RATIO)
  boys += childsex

 print('{0} - total {1}, M/F ratio : {2}/{3}'.format(i + 1, families, boys, families - boys))

 totalboys += boys
 totalgirls += families - boys

 # Only families who gave birth a boy will be calculated next loop
 families = boys

 if(boys == 0):
  break

print('total children : {0}, boys : {1}, girls {2}'.format(totalboys + totalgirls, totalboys, totalgirls))