You will receive 3 points for solving this problem.

Manao is designing the genetic code for a new type of algae to efficiently produce fuel. Specifically, Manao is focusing on a stretch of DNA that encodes one protein. The stretch of DNA is represented by a string containing only the characters 'A', 'T', 'G' and 'C'.

Manao has determined that if the stretch of DNA contains a maximal sequence of consecutive identical nucleotides that is of even length, then the protein will be nonfunctional. For example, consider a protein described by DNA string "GTTAAAG". It contains four maximal sequences of consecutive identical nucleotides: "G", "TT", "AAA", and "G". The protein is nonfunctional because sequence "TT" has even length.

Manao is trying to obtain a functional protein from the protein he currently has. Manao can insert additional nucleotides into the DNA stretch. Each additional nucleotide is a character from the set {'A', 'T', 'G', 'C'}. Manao wants to determine the minimum number of insertions necessary to make the DNA encode a functional protein.
The input consists of a single line, containing a string *s* of length *n* (1 ≤ *n* ≤ 100). Each character of *s* will be from the set {'A', 'T', 'G', 'C'}.

This problem doesn't have subproblems. You will get 3 points for the correct submission.
import re

x = input()

l = [0 for i in range(len(x))]
c, h = 1, 0
for i in range(len(x) - 1):
    l, r = x[i], x[i + 1]
    if l is r:
        c += 1
    else:
        if c % 2 is 0:
            h += 1
        c = 1
        
if c % 2 is 0:
    h += 1
print(h)

# g = re.findall(r'G+', x)
# t = re.findall(r'T+', x)
# a = re.findall(r'A+', x)
# c = re.findall(r'C+', x)

# print(g, a, t, c)