We describe a vertex cover instance by writing the size of the graph <size> on
the first line, the size of the cover <cover> on the second, and on the
following lines the edges of the graph, where vertices are denoted by numbers 1
to <size>.

Example:
5
2
1 4
2 3
4 5

The above example describes a vertex cover instance with 5 vertices and edges
{1,4}, {2,3}, and {4,5} where we should find a vertex cover of size 2.
