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 <stdlib.h>
#include <math.h>

#define f(i, q) for(int i = 0; i < q; i++)  

typedef long long ll;

#define MAX 20001

// 昇順にソート
int asc_comp(const void* a, const void* b){
    ll x = *(ll*)a;
    ll y = *(ll*)b;
    return x - y;
}
// 降順にソート
int dec_comp(const void* a, const void* b){
    ll x = *(ll*)a;
    ll y = *(ll*)b;
    return y - x;
}

int main() {
    // qsort(in, a, sizeof(ll), dec_comp);
    char inp[MAX], oup[MAX];
    scanf("%s %s", inp, oup);
    ll at = 0, sum = 0;
    while(inp[at] != '\0') {
        if (inp[at] != oup[at]) {
            sum++;
        }
        at++;
    }
    printf("%lld\n", sum);

    return 0;
}