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 ff first
#define ss second
#define PI acos(-1)
#define pb push_back
#define int long long
#define ld long double
#define sp fixed<<setprecision
#define bp __builtin_popcountll
#define all(x) x.begin(),x.end()
#define pii pair<long long,long long>
#define FAST ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);

const int M = (1e9)+7;
const int N = 1e6+5;

signed main()
{
    FAST
    int tc=1;
    //cin>>tc;
    for(int ti=1;ti<=tc;ti++)
    {
        int n;
        string s,t;
        cin>>s>>t;
        n = s.length();
        int ans = 0;
        for(int i=0;i<n;i++)ans += (s[i]!=t[i]);
        cout<<ans<<endl;
    }
    return 0;
}