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)

#ifdef DEBUG

#else

#    pragma GCC optimize("O3,no-stack-protector")
#    pragma GCC optimize("unroll-loops")

#    if __cplusplus < 201703L
#        pragma GCC target("avx")
#    else
#        pragma GCC target("avx2")
#    endif

#endif

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define dump(x) cout << x << endl
typedef int64_t Int;
typedef long double Ld;

using namespace std;
using Graph = vector<vector<Int>>;

const Ld pi = M_PI;
const Int MOD = 1000000007;
const Int INF = 1LL << 61;

Int Floor(Int a, Int b) {
    return (a - (a % b)) / b;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    string s, t;
    cin >> s >> t;

    int ans = 0, ro = s.size();
    for (int i = 0; i < ro; i++) {
        if (s[i] != t[i]) {
            ans++;
        }
    }

    cout << ans << endl;

    return 0;
}