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<string>
#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;
using ll = long long;
using P = pair<ll, ll>;
#define REP(i, n) for(ll i = 0; i < (ll)n; i++)
#define RREP(i, n) for(ll i = (ll)(n-1); i >= 0; i--)
#define ALL(vector) vector.begin(), vector.end()

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    string s,t;
    cin>>s>>t;
    ll cnt=0;
    REP(i,s.size()){
        if(s[i] != t[i]) cnt++;
    }
    cout<<cnt<<endl;
    return 0;
}