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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using static Scanner;

class Program
{
    static void Main() => new Program().Solve();

    public void Solve()
    {
        string s = Read();
        string t = Read();
        int c = 0;
        for (int i = 0; i < s.Length; i++)
        {
            if (s[i] != t[i]) c++;
        }
        Console.WriteLine(c);
    }
}


static class Scanner
{
    static Queue<string> que = new Queue<string>();

    public static string Read()
    {
        if (!que.Any()) foreach (var s in Console.ReadLine().Split()) que.Enqueue(s);
        return que.Dequeue();
    }
    public static int ReadInt() => int.Parse(Read());
    public static long ReadLong() => long.Parse(Read());
    public static double ReadDouble() => double.Parse(Read());
    public static decimal ReadDecimal() => decimal.Parse(Read());

    public static IEnumerable<string> Read(long n)
    {
        for (long i = 0; i < n; i++) yield return Read();
    }
    public static IEnumerable<int> ReadInt(long n) => Read(n).Select(int.Parse);
    public static IEnumerable<long> ReadLong(long n) => Read(n).Select(long.Parse);
    public static IEnumerable<double> ReadDouble(long n) => Read(n).Select(double.Parse);
    public static IEnumerable<decimal> ReadDecimal(long n) => Read(n).Select(decimal.Parse);
}