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 forn(i, n) for (int i = 0; i < n; i ++)
#define for1(i, n) for (int i = 1; i <= n; i ++)
#define repn(i, n) for (int i = n-1; i >= 0; i --)
#define rep1(i, n) for (int i = n; i >= 1; i --)
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define f first
#define s second
using namespace std;
template <class Ch, class Tr, class Container>
basic_ostream <Ch, Tr> & operator << (basic_ostream <Ch, Tr> & os, Container const& x) {
    os << "{ ";
    for(auto& y : x) os << y << " ";
    return os << "}";
}
typedef long long ll;
const int INF = 1e9;
const ll INFl = 1e18;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;
typedef vector<ll> vll;
typedef queue<int> qi;
typedef queue<pii> qpii;

void test_case() {
	string a, b; cin >> a >> b;
	int ans = 0;
	for (int i = 0; i < (int)a.size(); i ++) {
		if (a[i] != b[i]) ans ++;
	}
		cout << ans << '\n';
}

int main() {
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	int q = 1;
	//cin >> q; 
	while (q--) {
		test_case();
	}
	return 0;
}