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: Accepted)

#define taskname "test"

#include <bits/stdc++.h>

using namespace std;

#define sz(x) (int)x.size()
#define fi first
#define se second

typedef long long lli;
typedef pair<int, int> pii;

string s, t;
int n;

void read_input()
{
    cin >> s >> t;
    n = sz(s);
}

void solve()
{
    int ans = 0;
    for(int i = 0; i < n; ++i)
        if(s[i] != t[i]) ++ans;
    cout << ans << '\n';
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    read_input();
    solve();
}