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: Wrong Answer)

import java.util.*;
import java.io.*;
import java.lang.*;
 
public class Main {

  static class FastReader {

    BufferedReader br; 
    StringTokenizer st; 

    public FastReader() { 
      br = new BufferedReader(new InputStreamReader(System.in)); 
    } 

    String next() { 
      while (st == null || !st.hasMoreElements()) { 
        try { 
          st = new StringTokenizer(br.readLine()); 
        } catch (IOException e) { 
          e.printStackTrace(); 
        } 
      } 
      return st.nextToken(); 
    } 

    int nextInt() { 
      return Integer.parseInt(next()); 
    } 

    long nextLong() { 
      return Long.parseLong(next()); 
    } 

    double nextDouble() { 
      return Double.parseDouble(next()); 
    } 

    String nextLine() { 
      String str = ""; 
      try { 
        str = br.readLine(); 
      } catch (IOException e) { 
        e.printStackTrace(); 
      } 
      return str; 
    } 
  }
 
  public static void main(String args[]) throws IOException {
    try {
      FileOutputStream output = new FileOutputStream("temp.out");
      PrintStream out = new PrintStream(output);
      //Diverting the output stream into file "temp.out".Comment the below line to use console
      System.setOut(out);
  
      InputStream input = new FileInputStream("temp.in");
      //Diverting the input stream into file "temp.in".Comment the below line to use console
      System.setIn(input);
  
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    }
  
    FastReader sc = new FastReader();
    PrintWriter wr = new PrintWriter(System.out);
 
    // int t = 1;
    // t = sc.nextInt();    //Comment this line if there is single test case
    
    // while((t--) != 0) {
  
    //   int x = sc.nextInt();
    //   int y = sc.nextInt();
      
    //   wr.println(x+y);
    // }

    String s = sc.nextLine();
    String t = sc.nextLine();

    int count = 0;

    for(int i = 0; i < s.length(); i++) {
      
      if(s.charAt(i) != t.charAt(i))
        count++;
    }

    wr.println(count);




    wr.flush();
    wr.close();
  }
}