B'There are n cities and m roads in Berland. Each road connects a pair of cities. The roads in Berland are one-way. What is the minimum number of new roads that need to be built to make all the cities reachable from the capital? New roads will also be one-way. The first line of input consists of three integers n , m and s ( 1 <= n <= 5000, 0 <= m <= 5000, 1 <= s <= n ) -- the number of cities, the number of roads and the index of the capital. Cities are indexed from 1 to n . The following m lines contain roads: road i is given as a pair of cities u_i , v_i ( 1 <= u_i, v_i <= n , u_i ne v_i ). For each pair of cities (u, v) , there can be at most one road from u to v . Roads in opposite directions between a pair of cities are allowed (i.e. from u to v and from v to u ). Print one integer -- the minimum number of extra roads needed to make all the cities reachable from city s . If all the cities are already reachable from s , print 0. The first example is illustrated by the following: For example, you can add roads ( 6, 4 ), ( 7, 9 ), ( 1, 7 ) to make all the cities reachable from s = 1 . The second example is illustrated by the following: In this example, you can add any one of the roads ( 5, 1 ), ( 5, 2 ), ( 5, 3 ), ( 5, 4 ) to make all the cities reachable from s = 5 . '...