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 (Clang 10.0.0) (judge verdict: Runtime Error)

#include<stdio.h>
int main() {

	int count=0;
	char s[20001], t[20001];

	scanf("%s%s", s, t);

	for (int i = 0; i <= 20001; i++) {
		if (s[i] == '\0') {
			break;
		}
		if (s[i] != t[i]) {
			count++;
		}
	}

	printf("%d", count);

	return 0;
}