Module Module1
    Function random(A As Integer, B As Integer) As Integer
        random = Int(Rnd() * (B - A + 1) + A)
    End Function

    Sub Main()
        Call Randomize()
        'Call randomValues()
        'Call rectangle()
        Call prob8()
    End Sub

    Sub randomValues()
        Dim r As Integer
        Dim sum As Integer
        sum = 0
        Dim n As Integer
        Console.Write("Put some number: ")
        n = Console.ReadLine()
        Dim num As Integer
        num = 0
        Dim max As Integer
        max = 0
        Do While sum <= n
            r = random(0, 100)
            Console.WriteLine("Random: " & r)
            sum = sum + r
            num = num + 1
            If r > max Then
                max = r
            End If
        Loop
        Console.WriteLine("Sum:    " & sum)
        Console.WriteLine("Average:" & sum / num)
        Console.WriteLine("Maximum:" & max)

    End Sub

    Sub passCheck()
        Dim password As String
        password = "Admin1234"
        Dim userPass As String
        Do
            Console.Write("Enter password: ")
            userPass = Console.ReadLine()
        Loop While password <> userPass

        'If password = userPass Then
        '    Console.WriteLine("Logged in")
        'Else
        '    Console.WriteLine("Wrong password")
        'End If

    End Sub

    Sub prob2()
        Dim number As Integer
        number = 1
        Dim max As Integer
        number = InputBox("Give a number")
        max = number
        Do While number Mod 5 <> 0
            number = InputBox("Give a number")
            If max < number Then
                max = number
            End If
        Loop
        Console.WriteLine("")
        Console.WriteLine("max number = " & max)
    End Sub



    Sub rectangle()
        Dim w As Integer
        Dim h As Integer
        Console.Write("Height: ")
        h = Console.ReadLine()
        Console.Write("Width: ")
        w = Console.ReadLine()

        Dim i As Integer
        Dim j As Integer

        For j = 0 To h - 1
            Console.Write("X")
            For i = 0 To w - 3
                If j = h - 1 Or j = 0 Then
                    Console.Write("X")
                Else
                    Console.Write(" ")
                End If
            Next i
            Console.WriteLine("X")
        Next j

    End Sub

    Sub prob4()
        Dim r As Double
        Do
            r = InputBox("define radius")
        Loop While r <= 0
        Console.WriteLine("Area = " & Math.PI * r ^ 2)
        Console.WriteLine("Circumference = " & 2 * Math.PI * r)
    End Sub

    Sub prob5()
        Dim a As Integer
        Dim b As Integer
        Dim decision As Integer
        a = InputBox("First number")
        b = InputBox("Second number")
        decision = InputBox("Chose operation: 1-Sum, 2-Subtraction, 3-Multiplication, 4-Division, 5-Power, 6-Modulo")
        If decision = 4 Or decision = 6 Then
            Do While b = 0
                b = InputBox("b cannot be 0 for choosen operation. Define b again")
            Loop
        End If
        If decision = 1 Then
            MsgBox("Sum: " & (a + b))
        ElseIf decision = 2 Then
            MsgBox("Subtraction: " & (a - b))
        ElseIf decision = 3 Then
            MsgBox("Multiplication: " & (a * b))
        ElseIf decision = 4 Then
            MsgBox("Division: " & (a / b))
        ElseIf decision = 5 Then
            MsgBox("Power: " & (a ^ b))
        ElseIf decision = 6 Then
            MsgBox("Modulo: " & (a Mod b))
        Else
            MsgBox("ERROR - wrong operation number")
        End If
    End Sub

    Sub prob6()
        Dim a As Integer
        Dim b As Integer
        Dim gcd As Integer
        Do
            a = InputBox("Define a")
        Loop While a <= 0
        Do
            b = InputBox("Define b")
        Loop While b <= 0

        Do While a <> b
            If a > b Then
                a = a - b
            Else
                b = b - a
            End If
        Loop
        gcd = a
        Console.Write("GCD = " & gcd)
    End Sub

    Sub prob7()
        Dim points As Double
        Dim sum As Double
        Dim g As Double
        Do
            Do

                points = InputBox("Give number of points")
                If points < 0 Or points > 10 Then
                    MsgBox("wrong number of points, it should be from interval [0,10]. Specify it again.")
                End If
            Loop While points < 0 Or points > 10
            sum = sum + points
        Loop While sum <= 32
        If sum < 16 Then
            g = 2
        ElseIf sum < 21 Then
            g = 3
        ElseIf sum < 25 Then
            g = 3.5
        ElseIf sum < 28 Then
            g = 4
        ElseIf sum < 31 Then
            g = 4.5
        Else
            g = 5
        End If
        Console.WriteLine("Your grade is " & g)

    End Sub

    Sub prob8()
        Dim e As Double
        e = 1 * 10 ^ -10
        Dim ai As Double
        Dim s As Double
        Dim q As Double
        Dim i As Integer
        q = 0.3

        Do
            Console.WriteLine("Element i = " & i & " equals = " & ai)
            ai = q ^ i
            s = s + ai
            i = i + 1
        Loop While Math.Abs(ai) >= e
        Console.WriteLine("")
        Console.WriteLine("Sum of S " & s)
        Console.WriteLine("Analitycal sum of S " & 1 / (1 - q))
        Console.WriteLine("Error " & 1 / (1 - q) - s)

        'recursive version:
        Console.WriteLine("Recursive version:")
        i = 1
        ai = 1
        s = 1
        Do
            Console.WriteLine("Element i = " & i & " equals = " & ai)
            ai = ai * q
            s = s + ai
            i = i + 1
        Loop While Math.Abs(ai) >= e
        Console.WriteLine("")
        Console.WriteLine("Sum of S " & s)
        Console.WriteLine("Analitycal sum of S " & 1 / (1 - q))
        Console.WriteLine("Error " & 1 / (1 - q) - s)


    End Sub
End Module