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 IOS ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define int  long long
#define rep(i,a,b)    for(int i=a;i<b;i++)
#define repn(i,a,b)   for(int i=a;i>=b;i--)
#define F first
#define S second
#define pii pair<int,int>
#define vi vector<int>
#define vii vector<pii>
#define pb push_back
#define mp  make_pair
#define all(v) (v).begin(), (v).end()
#define endl "\n"
#define mod 1000000007  
#define mod2 998244353 
const int N = 100001; 



void solve(){
    string a,b;
    cin>>a>>b;
    int ans=0;
    int n=a.length();
    rep(i,0,n){
        if(a[i]!=b[i])ans++;
    }
    cout<<ans;
    return ;
}
         
signed main(){
        IOS;

        // vi f(2e6+1);
        // f[0]=0;f[1]=0;f[2]=0;f[3]=4;
        // rep(i,4,2e6+1){
        //     f[i]=(f[i-1]+2*f[i-2])%mod;
        //     if(i%3==0)f[i]=(f[i]+4)%mod;
        // }
        int t=1;
        // cin>>t;
        rep(i,0,t){
            solve();
            // int temp;cin>>temp;
            // cout<<f[temp];

            cout<<"\n";
        //   cout<<" * "<<t<<"\n";
        }
    //    return 0;
}