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 C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int main()
{
    char s[200000];
    char t[200000];
    int i;
    int num;
    if (scanf("%s", s) < 0)
    {
        fprintf(stderr, "error\n");
        return 0;
    }
    if (scanf("%s", t) < 0)
    {
        fprintf(stderr, "error\n");
        return 0;
    }
    i = 0;
    num = 0;
    while (t[i])
    {
        if (t[i] == s[i])
            num++;
        i++;
    }
    printf("%d", num);
    return 0;
}