C :: Drawing Hollow Triangle Given User Input Indicating Number Of Rows

How to draw a hollow triangle given a user input indicating the number of rows.

Eg:
Number of rows = 4
___*
__*_*
_*___*
*******

My idea was to split up the triangle into three parts (first row, middle part, last row) and I've managed to write some code on printing the first and last row of the triangle

Code:
int main() {
//Declaring the variables.
int rows, position;
//Prompts user to enter number of rows.
printf("Enter the number of rows in the triangle: ");
scanf("%d", &rows);

[Code] .....

What to do so that I can print the middle part of the triangle. All I know is that I need to use loops. I've also been told that drawing a flow chart would work but I really don't know how to even begin with a flow chart then transform it into code.