An easy avoiding of a bug

The functional interfaces are removed.
Better solution could be a reference counted core of the io interfaces

Now it is huge work so just write that:

GraphReader<ListGraph>(std::cin, graph).

Instead of:

graphReader(std::cin, graph).

c LEMON max flow problem

p max 7 9

n 1 s

n 7 t

a 1 2 3

a 1 3 2

a 1 4 1

a 2 5 3

a 3 5 2

a 3 7 5

a 3 6 3

a 4 6 1

a 5 7 2

a 6 7 4