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>
#define optimize ios_base::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0) ;
#define ll long long
#define ld long double
#define vi vector<int>
#define si set<int>
#define vc vector<char>
#define vb vector<bool>
#define vll vector<ll>
#define vd vector<double>
#define lb(v,x) lower_bound(v.begin(), v.end(), x) - v.begin()
#define up(v,x) upper_bound(v.begin(), v.end(), x) - v.begin() - 1
#define pb push_back
#define lp(i,a,b) for(int i = a ; i <= b ; i ++)
#define rlp(i,a,b) for(int i = b ; i >= a ; i --)
#define a_sort(v) sort(v.begin(), v.end())
#define d_sort(v) sort(v.rbegin(), v.rend())
#define vin(v) for(auto &x : v) cin >> x
#define vout(v) for(auto x : v) cout << x << ' ' ; cout << endl
#define pii pair<int,int>
#define pll pair<ll,ll>
#define mp make_pair
#define pi 3.14159265358979323846264338327950
using namespace std ;
// #define debug

const int MOD = 1E9 + 7 ;
const int N = 1E5 ;

int main() {
    #ifdef debug
    freopen("input.txt", "r", stdin) ;
    freopen("output.txt", "w", stdout) ;
    #endif // debug
    optimize

    string s ; cin >> s ;
    string t ; cin >> t ;
    int cnt = 0 ;
    lp(i, 0, s.size() - 1) if(s[i] != t[i]) cnt ++ ;
    cout << cnt << endl ;
}