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: Wrong Answer)

using System;
using System.Text;

namespace _171_b
{
    internal class MinorChange
    {
        private static void Main(string[] args)
        {
            var input1 = GetInputString();
            var input2 = GetInputString();

            var length = input1.Length - 2;

            var identicalCount = 0;
            for (var i = 0; i < length; i++)
            {
                if (input1[i] != input2[i])
                {
                    identicalCount++;
                }
            }

            Console.WriteLine(identicalCount);
        }
        
        private static string GetInputString()
        {
            var sb1 = new StringBuilder();
            while (true)
            {
                var ch = Convert.ToChar(Console.Read());
                sb1.Append(ch);
                if (ch == '\n') break;
            }
            return sb1.ToString();
        }
    }
}