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* line1;
  char* line2;
  int i;
  int n;
  int cnt;
  line1 = (char*)malloc(sizeof(char)*200001);
  line2 = (char*)malloc(sizeof(char)*200001);
  fgets(line1, 200001, stdin);
  fgets(line2, 200001, stdin);
  n = strlen(line1);
  cnt = 0;
  for ( i = 0; i < n; i++ ) {
    if (line1[i] != line2[i]) {
      cnt++;
    }
  }
  printf("%d\n", cnt);
  free(line1);
  free(line2);
  return 0;
}