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() => new Program().Solve();

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

	#region Console.Read 関係
	long[] ReadLongArray() => Array.ConvertAll(Console.ReadLine().Split(), long.Parse);
	long ReadLong() => long.Parse(Console.ReadLine());
	#endregion
}