#42869: python 簡易程式 只有15行
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(薛冠志)
while True:
try:
s = list(map(int,input()))
a = []
b = []
for i,d in enumerate(s):
if i % 2 == 0:
a.append(d)
else:
b.append(d)
num = int((sum(a)-sum(b)))
print(abs(num))
except:
break