Unexpected Error

printf("%d %d", 1ll, 1ll);

This will not output the expected result. A 64-bit integer will not cooperate with a %d argument.

So, instead

printf("%d %d", (int)1ll, (int)1ll);

or

printf("%I64d %I64d", 1ll, 1ll);

or

printf("%lld %lld", 1ll, 1ll);

should be used.

Strongly Connected Components

//Graph
//Strongly Connected Components

//call DFS(G) to compute finishing times f[u] for each vertex u
//compute GT, the transpose of G
//call DFS(GT), but in the main loop of DFS, consider the vertices
// in order of decreasing f[u] (as computed in line 1)
//output the vertices of each tree in the depth-first forest formed in line 3 as
// a separate strongly connect component

First Unscheduled System Down

We experienced the first unscheduled system down today. The reason is that the server of our service provider met some unforeseen problem.

Now, problems are fixed and data seems not affected.