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>
#include<stdlib.h>
#include<string.h>

int main()
{
    int x = 0;
    char n[200000];
    char m[200000];
    char buf[200000];

    //標準入力から一行をbufに格納
    fgets(buf, sizeof(buf), stdin);

    strcpy(n,buf);
    
    fgets(buf, sizeof(buf), stdin);

    strcpy(m,buf);
    
    for (int i = 0; i < strlen(n); i++)
    {
        if (n[i] != m[i])
        {
            m[i] = n[i];
            x += 1;
        }
    }

    //標準入力に書き出す
    printf("%d\n", x);
}