Inversions

n = input().rstrip()
a, b = 0, 0
for i, el in enumerate(n):
 if i % 2 == 0:
  if el == '0':
   b += 1
  else:
   a += 1
 else:
  if el == '0':
   a += 1
  else:
   b += 1

print(min(a,b))

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED