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.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class Main {

   private static final String INPUT_FILE_PATH = "";

   static void solve(InputReader in, PrintWriter out) {
      String s = in.nextToken();
      String t = in.nextToken();
      int ans = 0;
      for (int i = 0; i < s.length(); i++) {
         if (s.charAt(i) != t.charAt(i)) ans++;
      }
      out.println(ans);
   }

   private static class InputReader {
      private BufferedReader br;
      private StringTokenizer st;

      public InputReader(InputStream inputStream) {
         this.br = new BufferedReader(new InputStreamReader(inputStream), 32768);
         this.st = null;
      }

      public String nextToken() {
         while (st == null || !st.hasMoreTokens()) {
            try {
               st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
               throw new RuntimeException(e);
            }
         }
         return st.nextToken();
      }

      public int nextInt() {
         return Integer.parseInt(nextToken());
      }

      public long nextLong() {
         return Long.parseLong(nextToken());
      }

      public double nextDouble() {
         return Double.parseDouble(nextToken());
      }
   }

   public static void main(String[] args) throws Exception {
      InputStream inputStream = INPUT_FILE_PATH.isEmpty()
         ? System.in
         : new FileInputStream(new File(INPUT_FILE_PATH));
      OutputStream outputStream = System.out;

      InputReader inputReader = new InputReader(inputStream);
      PrintWriter printWriter = new PrintWriter(outputStream);

      solve(inputReader, printWriter);

      printWriter.close();
   }

}