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 Python (3.8.2) (judge verdict: Runtime Error)

def distance(x, y):
    return (x ** 2 + y ** 2) ** (1 / 2)


def main():
    n, d = map(int, input().split())
    xy_lst = [list(map(int, input().split())) for _ in range(n)]
    count = 0

    for i in range(n):
        x = xy_lst[i][0]
        y = xy_lst[i][1]
        if distance(x, y) <= d:
            count += 1

    print(count)


if __name__ == '__main__':
    main()