Error Index out of range - why does it come up when i am validating?

Question

I am learning C# programming i bumped into this error. Question --> Write a program and ask the user to enter 5 numbers. If a number has been previously entered, display an error message and ask the user to re-try. Once the user successfully enters 5 unique numbers, sort them and display the result on the console.

I know the easiest way to solve this is using List but since i am learning I wanted to try arrays.

I don't understand what is it that i am doing wrong

Thanks for your help!!

public void Excercise3()
        {
            Console.WriteLine("Please enter unique numbers");
            int[] number = new int[5];
            for (var i = 0; i <= 5; i++)
            {
                var input = Console.ReadLine();
                if (String.IsNullOrWhiteSpace(input))
                    break;
                
                var intInput = int.Parse(input); 
                foreach(int x in number)  
                    if(number[x] != intInput) { 
                   
                     
                    number[i] = intInput;
                        //   Console.WriteLine(number[i]);

                    
                    }
                    else 
                    {
                        Console.WriteLine("You need to enter unique number");

                        break;
                    }
              
            }
            
        }```