Idea how to solve one problem

[mitko29]

Hello all today I found one problem which I think is very interesting.
On the picture below you can see blue points which are X & Y coordinates.
After entering all X & Y points they need to be connected like the second picture.
My idea first was to solve it this way:
1.Read data from TextFile.
2.Then find the lowest point which in my case is [X:1,Y:1] and set it like a start point.
3.Then increase the Y coordinate and find the second point , when it's found the program set it as start and so on,but after applying these ideas on paper all fail.


Second link for picture:


Can you give me some idea how to solve it ?