using System;

public class Program

{

    public static void Main()

    {

        login();

        checkChar();

        evenOrOdd();

        ifString();

        removeACharacter();

        exchangeFirstAndLast();

        rangeBetween20And50();

        closerTo100();

        between20And30();

        letterZ1to4Times();

        startsWithString();

    }

    //1 

    public static void login()

      {

         string username="Ayanda", password="aya123";

​

            Console.WriteLine("Enter your username>>");

            string inputUser = Console.ReadLine();

            Console.WriteLine("Enter your password>>");

            string inputPass = Console.ReadLine();

            if(username == inputUser && password == inputPass)

            {

                Console.WriteLine("Well done, your details have been saved!");

            }

            else{

                for(int i= 1 ; i < 3 ; i++)

                {

                    Console.WriteLine("Enter your username>>");

                    inputUser = Console.ReadLine();

                    Console.WriteLine("Enter your password>>");

                    inputPass = Console.ReadLine();

                    if(username == inputUser && password == inputPass)

                    {

                        Console.WriteLine("Well done, your details have been saved!");

                        break;

                    }

                    else

                        continue;

                }

            }

​

     }

    //2

    public static void checkChar()

    {

        Console.WriteLine("Enter a char ");

        string input = Console.ReadLine();

        Char [] c = input.ToCharArray();

        if(Char.IsDigit(c[0]))

            Console.WriteLine(c[0]+ " is a digit");

        if((Char.IsLower(c[0])) && (c[0]=='a' || c[0]=='e'||c[0]=='i' || c[0]=='o' ||c[0]=='u') )

            Console.WriteLine(c[0]+ " is a lowercase vowel");

        if(Char.IsSymbol(c[0]))

            Console.WriteLine(c[0]+ " is a symbol");

    }

    //3

    public static void evenOrOdd()

    {

        Console.WriteLine("Enter a number ");

        int number1 = Convert.ToInt32(Console.ReadLine());

        Console.WriteLine("Enter a second number ");

        int number2 = Convert.ToInt32(Console.ReadLine());

        if((number1%2 ==0) && (number2%2==0))

            Console.WriteLine(true);

        else if(!(number1%2==0) && !(number2%2==0))

            Console.WriteLine(true);

            else

                Console.WriteLine(false);

    }

    //4

    public static void ifString()

    {

        Console.WriteLine("Enter a word ");

        string input = Console.ReadLine();

        if(input.StartsWith("if"))

            Console.WriteLine(input);

        else{

            input = input +"if";

            Console.WriteLine(input);

        }

    }

    //5

    public static void removeACharacter()

    {

        Console.WriteLine("Enter a word ");

        string input = Console.ReadLine();

        Console.WriteLine("Enter a integer ");

        int index = Convert.ToInt32(Console.ReadLine());

        string newInput = input.Remove(index,1);

        Console.WriteLine("Result with removed character: "+newInput);

    }

    //6

    public static void exchangeFirstAndLast()

    {

        Console.WriteLine("Enter a word ");

        string input = Console.ReadLine();

        Char [] c = input.ToCharArray();

        Char first = c[0];

        Char last = c[c.Length -1];

        c[0] = last;

        c[c.Length -1] = first;

        string newInput = new string(c);

        Console.WriteLine(newInput);

    }

    //7

    public static void rangeBetween20And50()

    {

        Console.WriteLine("Enter the first number ");

        int number1 = Convert.ToInt32(Console.ReadLine());

        Console.WriteLine("Enter the second number ");

        int number2 = Convert.ToInt32(Console.ReadLine());

        Console.WriteLine("Enter the third number ");

        int number3 = Convert.ToInt32(Console.ReadLine());

        if((number1 > 20 && number1 < 50) || (number2 > 20 && number2 < 50) || (number2 > 20 && number2 < 50))

            Console.WriteLine(true);

        else

            Console.WriteLine(false);

    }

    //8

    public static void closerTo100()

    {

        Console.WriteLine("Enter the first number ");

        int number1 = Convert.ToInt32(Console.ReadLine());

        Console.WriteLine("Enter the second number ");

        int number2 = Convert.ToInt32(Console.ReadLine());

        int min = 0;

        if(number1 < 100)

            min = number1;

        if(number2 > min)

            min = number2;

        Console.WriteLine(min);

    }

    //9

    public static void between20And30()

    {

        Console.WriteLine("Enter the first number ");

        int number1 = Convert.ToInt32(Console.ReadLine());

        Console.WriteLine("Enter the second number ");

        int number2 = Convert.ToInt32(Console.ReadLine());

        if((number1 > 20 && number1 < 30) || (number2 > 20 && number2 < 30))

        {

            if(number1 > 20 && number1 < 30) 

            Console.WriteLine(number1);

                if (number2 > 20 && number2 < 30)

                Console.WriteLine(number2);

        }       

        else{

            Console.WriteLine(0);

        }

    }

    //10

    public static void letterZ1to4Times()

    {

        Console.WriteLine("Enter a string ");

        string input = Console.ReadLine();

        Char [] cInput = input.ToCharArray();

        int i=0;

        foreach( Char c in cInput)

        {

            if(c == 'z')

                i++;

        }

            if(i >=1 && i < 4)

            {

                Console.WriteLine(true);

            }

            else{

                Console.WriteLine(false);

            }

    }

    //11

    public static void startsWithString()

    {

        Console.WriteLine("Enter a string ");

        string input = Console.ReadLine();

        if(input.StartsWith("F"))

        {

            Console.WriteLine("Free");

        }

        if(input.EndsWith("B"))

        {

            Console.WriteLine("Bee");

        }

        if(input.StartsWith("F") && input.EndsWith("B"))

        {

            Console.WriteLine(true +" Free Bee");

        }

        else{

            Console.WriteLine(false +" "+input);

        }

    }

}