2.
k
3.
k
4. n :
5. 0<n
6.
x,y:k. y-x = n-1 
(
L:(k-1) List. (x, y) = compose_flips(L))
7. x1 :
k
8. y1 :
k
9. y1-x1 = n
10. L :
(k-1) List
11. (x1+1, y1) = compose_flips(L)
12.
y1 = x1+1
13. (x1, y1) = compose_list([(x1, x1+1); (y1, x1+1); (x1, x1+1)])
L:(k-1) List. (x1, y1) = compose_flips(L)
