import sys

sys.setrecursionlimit(10**7)

s = list(eval(input()))

t = list(eval(input()))



if s == t: print((0), sys.exit())



cnt = 0

for i in range(len(s)):

    if t[i] != s[i]:

        t[i] = s[i]

        cnt += 1

print(cnt)
import sys



s = list(eval(input()))

t = list(eval(input()))



if s == t: print((0), sys.exit())



"""

cnt = 0

for i in range(len(s)):

    if t[i] != s[i]:

        # t[i] = s[i]  # いらない

        cnt += 1

print(cnt)

"""



#  zip関数での別解

res = len([1 for i, j in zip(s, t) if i != j])

print(res)
import sys

sys.setrecursionlimit(10**7)
s = list(eval(input()))
t = list(eval(input()))
if s == t:
    print((0), sys.exit())
cnt = 0
for i in range(len(s)):
    if t[i] != s[i]:
        t[i] = s[i]
        cnt += 1
print(cnt)

import sys

s = list(eval(input()))
t = list(eval(input()))
if s == t:
    print((0), sys.exit())
"""
cnt = 0
for i in range(len(s)):
    if t[i] != s[i]:
        # t[i] = s[i]  # いらない
        cnt += 1
print(cnt)
"""
#  zip関数での別解
res = len([1 for i, j in zip(s, t) if i != j])
print(res)

-sys.setrecursionlimit(10**7) +""" -        t[i] = s[i] +        # t[i] = s[i]  # いらない +""" +#  zip関数での別解 +res = len([1 for i, j in zip(s, t) if i != j]) +print(res)