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 i,j in zip(s,t):

    if i != j:

        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 i, j in zip(s, t):
    if i != j:
        count += 1
print(count)

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