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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.awt.*;
import java.util.*;
import java.io.*;
import java.math.BigDecimal;
import java.nio.file.Files;
import java.nio.charset.StandardCharsets;
//给出两个数a,b 求出[a,b]中各位数字之和能整除原数的数的个数。
public class Main {
    int mod  = (int) 1e9+7;
    //int n = (int) 1e6+5;
    //long[][] memo = new long[n][27];
    void solve(String s1, String s2) {
        char[] cs1 = s1.toCharArray();
        char[] cs2 = s2.toCharArray();
        int n = s1.length();
        int cnt = 0;
        for(int i=0;i<n;i++){
            if(cs1[i]!=cs2[i])cnt++;
        }
        System.out.println(cnt);
    } 
    //0 1 2 3 4 5 6 7
    //1 7 3 4 7 6 2 9
    //1 7 4 3 7 6 2 9;
    //1 2 1 2 1
    public static void main(String[] args)  throws IOException {
        // Use the Scanner class

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        //String[]  s = br.readLine().split(" ");
        Main test = new Main();

        String s = br.readLine();
        String s2 = br.readLine();
        test.solve(s,s2);
    }
}