Flow diagram of the cycle. Theory

I go through testing at a distance in cycles, according to the condition of the task, I have to write a utility with only the flowchart given below:

The third and fifth blocks are called the upper and lower bounds of the condition. Also, the course provides a description of this flowchart. But it also confuses me:

But if this flowchart means the "if" condition, then "if" has its own notation, just like for "while", "do while", and others. I fail all the questions that are related to this flowchart. Thank you for your answer, Amateur. Akina, even if I implement the simplest Loop in C# type:

static int SumDoWhile()
{
    //
    // Sum numbers 0 .. 4
    //
    int sum = 0;
    int i = 0;
    do
    {
    sum += i;
    i++;
    } while (i < 5);
    return sum;
}

Then the flowchart to it will look like:

Cassini, do I understand you correctly that the drawing of the very first flowchart can be described as follows:

public delegate void TopMessage(string message);
    class Program
    {

       static void Main(string[] args)
        {
            int a = 0;
            int b = 1;
            do
            {
                b = b + a;
                a++;
            }
            while (a < 5);
            Console.WriteLine(a);
            Console.ReadLine();
        }

And it will be correct?