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 int long long
#define pb push_back
#define inf 1e9
#define mod 1000000007
#define ff first
#define ss second

void solve()
{
	string s1, s2;
	cin >> s1 >> s2;

	int ans = 0;
	for (int i = 0; i < s1.length(); i++)
	{
		if (s1[i] != s2[i])
			ans++;
	}
	cout << ans << "\n";
}

signed main()
{
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	solve();
	return 0;
}