Inversions

bits = list(input().rstrip())
n = len(bits)
flip = False
valDict = {True: '1', False: '0'}
# true - 1
# false - 0
flip1 = 0
flip2 = 0
for i in range(n):
	#print(i)
	if bits[i] == valDict[flip]:
		flip1 += 1
		#print("incr flip1")
	else:
		#print("incr flip2")
		flip2 += 1
	flip = not flip
print(min(flip1, flip2))

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED