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.

Input

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 ≠ 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).

Output

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.

Examples

Input

9 9 1
1 2
1 3
2 3
1 5
5 6
6 1
1 8
9 8
7 1


Output

3


Input

5 4 5
1 2
2 3
3 4
4 1


Output

1

Note

The first example is illustrated by the following:

<image>

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:

<image>

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.
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.util.BitSet;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author kessido
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        EReachabilityFromTheCapital solver = new EReachabilityFromTheCapital();
        solver.solve(1, in, out);
        out.close();
    }

    static class EReachabilityFromTheCapital {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.NextInt();
            int m = in.NextInt();
            int s = in.NextInt() - 1;
            int[][] e = in.NextIntMatrix(m, 2, -1);
            int[][] g = GraphExtension.parseGraph_n_e_array_of_of_u_v_noSelfLoops(n, e, true);
            int[] componnent = GraphExtension.getStronglyConnectedComponnentMap(g);
            int[] componnentIn = new int[n];
            Arrays.fill(componnentIn, -1);
            for (int i = 0; i < n; i++) {
                componnentIn[componnent[i]] = 0;
            }
            for (int i = 0; i < n; i++) {
                for (int j : g[i]) {
                    if (componnent[i] != componnent[j]) {
                        componnentIn[componnent[j]]++;
                    }
                }
            }
            int res = 0;
            for (int i = 0; i < n; i++) {
                if (i == componnent[s]) continue;
                if (componnentIn[i] == 0) res++;
            }
            out.println(res);
        }

    }

    static class MatrixExtension {
        public static int[][] copy(int[][] mat) {
            if (mat.length == 0) return new int[0][0];
            int[][] res = new int[mat.length][mat[0].length];
            for (int i = 0; i < mat.length; i++) {
                System.arraycopy(mat[i], 0, res[i], 0, mat[i].length);
            }
            return res;
        }

    }

    static class GraphExtension {
        public static int[][] parseGraph_n_e_array_of_of_u_v_noSelfLoops(final int n, final int[][] e, final boolean directed) {
            int[] edgesCount = new int[n];
            for (int[] i : e) {
                edgesCount[i[0]]++;
                if (!directed)
                    edgesCount[i[1]]++;
            }
            int[][] graph = new int[n][];
            for (int i = 0; i < n; i++) {
                graph[i] = new int[edgesCount[i]];
            }
            for (int[] i : e) {
                graph[i[0]][--edgesCount[i[0]]] = i[1];
                if (!directed)
                    graph[i[1]][--edgesCount[i[1]]] = i[0];
            }
            return graph;
        }

        public static int[][] getGraph_no_self_loop_ToEdges_list(final int[][] graph, boolean directed) {
            int edgeCount = 0;
            int n = graph.length;
            for (int i = 0; i < n; i++) {
                edgeCount += graph[i].length;
            }
            if (!directed)
                edgeCount /= 2;
            int[][] res = new int[edgeCount][2];
            for (int i = 0; i < n; i++) {
                for (int j : graph[i]) {
                    if (directed || i < j) {
                        res[--edgeCount][0] = i;
                        res[edgeCount][1] = j;
                    }
                }
            }
            return res;
        }

        public static int[][] getReverseDirectedGraph(int[][] g) {
            return getReverseDirectedGraphFromEdges(g.length, getGraph_no_self_loop_ToEdges_list(g, true));
        }

        public static int[][] getReverseDirectedGraphFromEdges(int n, int[][] e) {
            e = MatrixExtension.copy(e);
            for (int[] e1 : e) {
                int t = e1[0];
                e1[0] = e1[1];
                e1[1] = t;
            }
            return parseGraph_n_e_array_of_of_u_v_noSelfLoops(n, e, true);
        }

        public static int[] getStronglyConnectedComponnentMap(int[][] g) {
            return new GraphExtension.StronglyConnectedComponnentFinder(g).getStronglyConnectedComponentsMap();
        }

        private static class StronglyConnectedComponnentFinder {
            final int n;
            final BitSet visited;
            final int[] queue;
            final int[] map;
            int queueIndex;
            final int[][] g;
            final int[][] gReverse;

            public StronglyConnectedComponnentFinder(int[][] g) {
                this.g = g;
                gReverse = getReverseDirectedGraph(g);
                n = g.length;
                queue = new int[n];
                queueIndex = n;
                map = new int[n];
                Arrays.fill(map, -1);
                visited = new BitSet(n);
            }

            int[] getStronglyConnectedComponentsMap() {
                for (int i = 0; i < n; i++) {
                    dfsForward(i);
                }
                for (int i = 0; i < n; i++) {
                    dfsReverse(queue[i], queue[i]);
                }
                return map;
            }

            void dfsForward(int i) {
                if (visited.get(i)) return;
                visited.set(i, true);
                for (int j : g[i]) dfsForward(j);
                queue[--queueIndex] = i;
            }

            void dfsReverse(int i, int root) {
                if (map[i] != -1) return;
                map[i] = root;
                for (int k : gReverse[i]) dfsReverse(k, root);
            }

        }

    }

    static class InputReader {
        BufferedReader reader;
        StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine(), " \t\n\r\f,");
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int NextInt() {
            return Integer.parseInt(next());
        }

        public int[][] NextIntMatrix(int n, int m, int offset) {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = NextInt() + offset;
                }
            }
            return a;
        }

    }
}

