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(){
    char buff1[10000];
    char buff2[10000];

    if(fgets(buff1,sizeof(buff1),stdin)== NULL) return -1;
    if(fgets(buff2,sizeof(buff1),stdin)== NULL) return -1;
    int cnt = 0;
    for (int i = 0;i<=strlen(buff1);i++){
        if (buff1[i] != buff2[i]){
            cnt ++;
        }
    }
    
    printf("%d\n",cnt);
    return 0;
}