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 forn(i, n) for(int i=0; i<n; i++)
#define M_PI 3.14159265358979323846
#define MOD 1000000007
typedef long long ll;
typedef vector<int> vint;
typedef vector<vint> vvint;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef pair<int, int> ipair;
typedef pair<ll, ll> llpair;

string s, t;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL), cout.tie(NULL);
    cin>>s>>t;
    int n = s.length(), ans = 0;
    for(int i=0; i<n; i++)
        if(s[i]!=t[i]) ans++;
    cout<<ans<<"\n";
    return 0;
}