What is the inverse of the following statement?

"If a shape has four sides, then it is not a triangle."

If a shape has four sides, then it is a triangle.
If a shape is not a triangle, then it has four sides.
If a shape does not have four sides, then it is a triangle.
If a shape is a triangle, then it does not have four sides

If a shape does not have four sides, then it is not a triangle.