S=eval(input())

T=eval(input())

count=0

for i in range(len(S)):

    if S[i]!=T[i]:

        count+=1

print(count)
S = eval(input())

T = eval(input())

count = 0

for s, t in zip(S, T):

    if s != t:

        count += 1

print(count)
S = eval(input())
T = eval(input())
count = 0
for i in range(len(S)):
    if S[i] != T[i]:
        count += 1
print(count)

S = eval(input())
T = eval(input())
count = 0
for s, t in zip(S, T):
    if s != t:
        count += 1
print(count)

-for i in range(len(S)): -    if S[i] != T[i]: +for s, t in zip(S, T): +    if s != t: