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>
using namespace std;

#define ll long long int
#define pb push_back
#define fi first
#define se second
#define mp make_pair
#define mt make_tuple
#define all(A) A.begin(), A.end()
#define sz(A) (int)A.size()
typedef vector <int> vi;
typedef vector <ll> vl;
typedef pair <int, int> pii;
typedef tuple <int, int, int> tii;
const ll mod = 1e9 + 7;
//const ll mod = 998244353;
const int inf = 1e9;
//const ll inf = 1e18;
const int N = 2e5;

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	#ifndef ONLINE_JUDGE
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
    #endif
	string s, t;
	cin >> s >> t;
	int cnt = 0;
	for (int i = 0; i < s.length(); i++) {
		if (s[i] != t[i])
			cnt++;
	}
	cout << cnt << "\n";
 	return 0;
}