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.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.StringTokenizer;
import java.util.BitSet;
import java.io.BufferedReader;
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 {
        int[][] g;
        BitSet visited;
        BitSet wasMain;
        int res = 0;

        void dfs(int i) {
            res++;
            wasMain.set(i, true);
            visited.set(i, true);
            for (int j : g[i]) {
                dfs2(j);
            }
        }

        void dfs2(int i) {
            if (visited.get(i)) {
                if (wasMain.get(i)) {
                    res--;
                    wasMain.set(i, false);
                }
            } else {
                visited.set(i, true);
                for (int j : g[i]) {
                    dfs2(j);
                }
            }
        }

        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.NextInt();
            int m = in.NextInt();
            int s = in.NextInt() - 1;
            g = GraphExtension.parseGraph_n_m_and_m_lines_of_u_v_noSelfLoops(n, m, in, false, true);
            GraphExtension.StronglyConnectedComponentResults stronglyConnectedComponent = GraphExtension.getStronglyConnectedComponent(g, true);
            g = stronglyConnectedComponent.g;
            s = stronglyConnectedComponent.map[s];
            visited = new BitSet(g.length);
            wasMain = new BitSet(g.length);
            dfs(s);
            wasMain.set(s, false);
            res--;
            int i = visited.nextClearBit(0);

            while (i < g.length) {
                dfs(i);
                i = visited.nextClearBit(i);
            }
            out.println(res);
        }

    }

    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;
        }

    }

    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[][] parseGraph_n_m_and_m_lines_of_u_v_noSelfLoops(final int n, final int m, final InputReader in, final boolean zeroBasedIndex, final boolean directed) {
            int[][] e = in.NextIntMatrix(m, 2, zeroBasedIndex ? 0 : -1);
            return parseGraph_n_e_array_of_of_u_v_noSelfLoops(n, e, directed);
        }

        public static GraphExtension.StronglyConnectedComponentResults getStronglyConnectedComponent(int[][] g, boolean withResultGraph) {
            return new GraphExtension.StronglyConnectedComponentFinder(g, withResultGraph).getStronglyConnectedComponents();
        }

        public static class StronglyConnectedComponentResults {
            public final int[] map;
            public final int[][] g;

            public StronglyConnectedComponentResults(int[] map, int[][] g) {
                this.map = map;
                this.g = g;
            }

        }

        private static class StronglyConnectedComponentFinder {
            private final int n;
            private final BitSet visited;
            private final BitSet onStack;
            private final int[] queue;
            private final int[] map;
            private final int[] low;
            private final int[][] g;
            private final boolean withResultGraph;
            ArrayList<int[]> new_graph = new ArrayList<>();
            int queueIndex = 0;
            int mapIndex = 0;
            private HashSet<Integer> hm = new HashSet<>();

            public StronglyConnectedComponentFinder(int[][] g, boolean withResultGraph) {
                this.withResultGraph = withResultGraph;
                this.g = g;
                n = g.length;
                queue = new int[n];
                queueIndex = 0;
                map = new int[n];
                low = new int[n];
                visited = new BitSet(n);
                onStack = new BitSet(n);
            }

            private void dfs(int i) {
                map[i] = low[i] = mapIndex++;
                queue[queueIndex++] = i;
                onStack.set(i, true);
                visited.set(i, true);
                for (int j : g[i]) {
                    if (!visited.get(j)) {
                        dfs(j);
                        low[i] = Math.min(low[i], low[j]);
                    } else if (onStack.get(j)) {
                        low[i] = Math.min(low[i], low[j]);
                    }
                }
                if (low[i] == map[i]) {
                    int newQueueIndex = queueIndex;
                    int currentSCCIndex = new_graph.size();
                    do {
                        map[queue[--newQueueIndex]] = currentSCCIndex;
                        onStack.set(queue[newQueueIndex], false);
                    } while (queue[newQueueIndex] != i);
                    if (withResultGraph) {
                        for (int j = newQueueIndex; j < queueIndex; j++) {
                            for (int k : g[queue[j]]) {
                                hm.add(map[k]);
                            }
                        }
                        hm.remove(currentSCCIndex);
                        int[] edges = new int[hm.size()];
                        int k = 0;
                        for (int j : hm) {
                            edges[k++] = j;
                        }
                        hm.clear();
                        new_graph.add(edges);
                    }
                    queueIndex = newQueueIndex;
                }
            }

            GraphExtension.StronglyConnectedComponentResults getStronglyConnectedComponents() {
                int i = 0;
                while (i < n) {
                    dfs(i);
                    i = visited.nextClearBit(i);
                }
                if (!withResultGraph)
                    return new GraphExtension.StronglyConnectedComponentResults(map, null);
                int[][] g = new int[new_graph.size()][];
                g = new_graph.toArray(g);
                return new GraphExtension.StronglyConnectedComponentResults(map, g);
            }

        }

    }
}

