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;

class Program
{

    static void Main(string[] args)
    {
        //入力
        var s = crS();
        var t = crS();
        int count = 0;
        for(int i = 0; i < s.Length; i++)
        {
            if (s[i] != t[i]) count++;
        }
        Console.WriteLine(count);
       
    }

   
  



        //入力受け取り用
    static string crS() { return Console.ReadLine(); }
    static int crI() { return int.Parse(Console.ReadLine()); }
    static int[] arrInt(){return Console.ReadLine().Split(' ').Select(v => int.Parse(v)).ToArray();}
    static long[] arrLong(){ return Console.ReadLine().Split(' ').Select(v => long.Parse(v)).ToArray(); }
    static string[] arrStr(){return Console.ReadLine().Split(' ').ToArray();}
    static List<int[]> mapInt(int h)
    {
        List<int[]> mapInt = new List<int[]>();
        for (int i = 0; i < h; i++)
        {
            mapInt.Add(arrInt());
        }
        return mapInt;
    }
}