//שאלה 3 

using System;

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double CalculateDifference(int n)

{

    double passSum = 0;

    double failSum = 0;

    int passCount = 0;

    int failCount = 0;

​

    int i = 0;

    while (i < n)

    {

        Console.Write("Enter your grade");

        double grade = double.Parse(Console.ReadLine());

​

        if (grade >= 55)

        {

            passSum += grade;

            passCount++;

        }

​

        if (grade < 55)

        {

            failSum += grade;

            failCount++;

        }

​

        i++;

    }

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    double passAverage = passCount > 0 ? passSum / passCount : 0;

    double failAverage = failCount > 0 ? failSum / failCount : 0;

​

    return passAverage - failAverage;

}

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Console.WriteLine("Enter the number of grades:");

int n = int.Parse(Console.ReadLine());

double difference = CalculateDifference(n);

Console.WriteLine("The difference between the averages is: " + difference);

​