Problem:
Score : 200 points

Problem Statement

Given are strings S and T. Consider changing S to T by repeating the operation below. Find the minimum number of operations required to do so.

Operation: Choose one character of S and replace it with a different character.

Constraints

S and T have lengths between 1 and 2\times 10^5 (inclusive).

S and T consists of lowercase English letters.

S and T have equal lengths.

Input

Input is given from Standard Input in the following format:

S
T

Output

Print the answer.

Sample Input 1

cupofcoffee
cupofhottea

Sample Output 1

4

We can achieve the objective in four operations, such as the following:

First, replace the sixth character c with h.

Second, replace the eighth character f with t.

Third, replace the ninth character f with t.

Fourth, replace the eleventh character e with a.

Sample Input 2

abcde
bcdea

Sample Output 2

5

Sample Input 3

apple
apple

Sample Output 3

0

No operations may be needed to achieve the objective.

Solution in PyPy3 (7.3.0) (judge verdict: Wrong Answer)

#https://atcoder.jp/contests/abc172/tasks/abc172_b

'''
<考え>
sとtを一文字ずつ比較し、異なる文字の数を出力
(s,tの長さが等しいと条件にある)
'''


#入力
s = str(input())
t = str(input())

#変数
count = 0

#必要な値を計算
l = len(s)

#処理
for i in range(l-1):
    print(s[i], t[i])
    if (s[i] != t[i]):
        count += 1

#出力
print(count)