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 Go (1.14.1) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func nextLine(r *bufio.Reader) string {
	var buf []byte
	for {
		line, isPrefix, err := r.ReadLine()
		if err != nil {
			panic(err)
		}
		buf = append(buf, line...)
		if !isPrefix {
			break
		}
	}
	return string(buf)
}

func nextStr(s *bufio.Scanner) string {
	s.Scan()
	ref := s.Bytes()
	cp := make([]byte, len(ref))
	copy(cp, ref)
	return string(cp)
}

func nextInt(s *bufio.Scanner) int {
	n, err := strconv.Atoi(nextStr(s))
	if err != nil {
		panic(err)
	}
	return n
}

func main() {
	// s := bufio.NewScanner(os.Stdin)
	// s.Split(bufio.ScanWords)
	r := bufio.NewReader(os.Stdin)

	S := nextLine(r)
	T := nextLine(r)

	fmt.Println(len(S))
	fmt.Println(len(T))
	ans := 0
	for i := 0; i < len(S); i++ {
		if S[i] != T[i] {
			ans++
		}
	}

	fmt.Println(ans)
}