What is the anwer for such construction:
2
2
10 20
50 60
2
10 20
50 60

is it stable?
But system of 2 bricks from second floor [10, 20] and [50, 60] have their center of mass in 35 which is not on brick.

Another example is sort of ladder:
4-ht level: [3, 6]
3-rd level: [2, 5]
2-nd level: [1, 4]
1-fs level: [0, 3]
in real word it is unstable, but what should I output?

The first one is stable, the second is not. Everything in this problem completely matches the real world.

The system of breaks falls if its center of masses doesn't stand on another break, i.e. like in real world.