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 INFTY 10000000000
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
typedef long long int ll;
const int MOD=1000000007;
const int di[4] = {-1,0,1,0};
const int dj[4] = {0,-1,0,1};

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