Reachability - MarisaOJ: Marisa Online Judge

Given a directed graph with

n

$n$ vertices and

m

$m$ edges, find the number of vertices that can be reached from every other vertex in the graph. ### Input - The first line contains 2 integers

n, m

$n,m$ . - The next

m

$m$ lines, each line contains two integers

u, v

$u, v$ , there is an edge between

u

$u$ and

v

$v$ . ### Output - Print the number of satisfied vertices. ### Constraints -

1 \leq n, m \leq 5 \times 10^{5}

$1 \le n,m \le 5 \times 10^5$ . -

1 \leq m \leq 10^{6}

$1 \le m \le 10^6$ . -

1 \leq u, v \leq n

$1 \le u,v \le n$ . ### Example Input:

651323344546

$6 5 1 3 2 3 3 4 4 5 4 6$

Output:

0

$0$

Topic

Graph

Rating

1300

Solution (0)

Solution