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)

#include <bits/stdc++.h>
#define ll long long
#define all(x) begin(x), end(x)
#define range(x) begin(x), begin(x)
#define what(x) cout << #x << ": " << x << '\n'
#define print(x) for (auto &el: x) cout << el << ' '; cout << '\n'
using namespace std;
 
template<typename S, typename T>
ostream& operator <<(ostream &os, pair<S, T> &m) { 
    os << '[' << m.first << " " << m.second << ']'; 
    return os; 
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    string a, b;
    cin >> a >> b;

    int n = a.size();
    int cnt = 0;
    for (int i = 0; i < n; ++i) {
        if (a[i] != b[i]) cnt++;
    }
    cout << cnt << endl;
    

    return 0;
}