소스 코드 :
data = list(map(int, input()))
zero_cnt = 0
one_cnt = 0
temp = data[0]
for i in range(1, len(data)):
if temp == data[i]:
temp = data[i]
continue
elif temp != data[i] and temp == 0:
temp = data[i]
zero_cnt += 1
elif temp != data[i] and temp == 1:
temp = data[i]
one_cnt += 1
print(min(zero_cnt, one_cnt))