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;
using ll=long long;
using ld=long double;
using ii=pair<ll,ll>;
using vi=vector<ll>;

#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define INF (ll)1e18
#define all(x) (x).begin(),(x).end()
#define print(a); for(auto x:a)cout<<x<<" "; cout<<"\n";
#define mset(a); memset(a,0,sizeof(a));

int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
    string s,t;cin>>s>>t;
    ll cnt=0;
    for(int i=0;i<s.size();i++){
        if(s[i]!=t[i])cnt++;
    }
    cout<<cnt<<"\n";
}