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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.StringTokenizer;

public class Main{

    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        String a = fs.next();
        String b = fs.next();
        int ans = 0;
        for(int i = 0; i < a.length(); i++){
            if(a.charAt(i) != b.charAt(i)) ans++;
        }
        System.out.println(ans);
    }

    static void sort(int[] a){
        ArrayList<Integer>l = new ArrayList<>();
        for(int i: a)
            l.add(i);
        Collections.sort(l);
        for(int i = 0; i < a.length; i++)
            a[i] = l.get(i);
    }

    static class FastScanner{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");
        String next(){
            while(!st.hasMoreTokens())
                try{
                    st = new StringTokenizer(br.readLine());
                } catch(IOException e){
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt(){
            return Integer.parseInt(next());
        }
        int[] readArray(int n){
            int[] a = new int[n];
            for(int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }
        long nextLong(){
            return Long.parseLong(next());
        }
    }
}