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<iostream>
#include<cmath>
#include<algorithm>
#include<vector>
#include<functional>
#include<string>
#include<iomanip>
#include<map>
#include<utility>
#include<string>
#include<unordered_map>
#include<queue>

template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }

using namespace std;

typedef long long ll;
typedef pair<int, int> P;
int gcd(int a, int b){return b ? gcd(b, a%b) : a;}
int lcm(int a, int b){return a*b / gcd(a, b);}



int main(){
    string s, t;
    cin >> s >> t;
    int ans = 0;
    for(int i = 0; i < s.size(); i++){
        if(s[i] != t[i]) ans++;
    }
    cout << ans << endl;
    return 0;
}