import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.util.ArrayList;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
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);
        DNastyaIsBuyingLunch solver = new DNastyaIsBuyingLunch();
        solver.solve(1, in, out);
        out.close();
    }

    static class DNastyaIsBuyingLunch {
        boolean[] vis;
        boolean[] visp;
        int[] pos;
        ArrayList<Integer>[] g;

        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int m = in.nextInt();
            int[] p = in.nextIntArray(n);
            vis = new boolean[n + 1];
            visp = new boolean[n + 1];
            g = new ArrayList[n];
            pos = new int[n];
            int[] count = new int[n];
            for (int i = 0; i < n; i++) {
                g[i] = new ArrayList<>();
                p[i]--;
                pos[p[i]] = i;
            }
            for (int i = 0; i < m; i++) {
                int u = in.nextInt() - 1;
                int v = in.nextInt() - 1;
                g[v].add(u);
                if (pos[v] > pos[u]) {
                    count[pos[u]]++;
                }
            }
            int pl = 0;
            dfs(p[n - 1]);
            for (int i = n - 1; i >= 0; i--) {
                if (visp[i]) pl++;
                else {
                    break;
                }
            }
            int pp = 0;
            for (int i = 0; i < n - 1; i++) {
                if (count[i] == n - i - 1) {
                    pp = 1;
                    break;
                }
            }
            out.print(Math.max(pl - 1, pp));
        }

        void dfs(int u) {
            vis[u] = true;
            visp[pos[u]] = true;
            for (int ele : g[u]) {
                if (vis[ele]) continue;
                dfs(ele);
            }
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        private boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public int[] nextIntArray(int size) {
            int[] array = new int[size];
            for (int i = 0; i < size; i++)
                array[i] = nextInt();
            return array;
        }

    }
}

