mainstr = "my mother is a grand wolf"
print(mainstr.replace("wolf", "bob"))

def binomial_coefficient(n, r):
  C = [0 for i in range(r+1)]
  C[0]=1
  for i in range(1,n+1):
    j = min(i,r)
    while j > 0:
      C[j] += C[j-1]
      j -= 1
    print(C)
  return C[r]

binomial_coefficient(4,4)