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: Runtime Error)

#include <stdio.h>
#include <string.h>
int chang(char* S, char* T)
{

	int cnt = 0;
	char tmp[1024];

	for (int i = 0; i <= strlen(S); i++)
	{
	
		if (S[i] != T[i])
		{
			//S[i] = T[i];
			cnt++;
		}
	}

	return cnt;
}
int main(void)
{
	char* S;
	char* T;
	
	printf("S=  ");
	scanf("%s", S);

	printf("\nT=  ");
	scanf("%s", T);
	
	if (strlen(S) != strlen(T))
	{
		printf("駄目だよ\n");
	}
	else if (strlen(S) == strlen(T))
	{
		printf("%d", chang(S, T));
	}
	else if (strlen(S) < 1)
	{
		printf("駄目だよ\n");
	}
}