import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.InputMismatchException;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        try (Scanner in = new Scanner(System.in)) {
            solve(in);
        }
    }

    private static void solve(Scanner in) {
        int N = in.nextInt(), M = in.nextInt();
        Graph G = new Graph(N);
        for (int i = 0; i < M; i++) {
            G.addEdge(in.nextInt() - 1, in.nextInt() - 1);
        }
        marked = new boolean[G.V()];
        int ans = paths(G, 0, 0);
        System.out.println(ans);
    }

    private static boolean[] marked;

    private static int paths(Graph G, int v, int i) {
        if (i == G.V() - 1) {
            return 1;
        }
        marked[v] = true;
        int paths = 0;
        for (int w : G.adj(v)) {
            if (!marked[w]) {
                paths += paths(G, w, i + 1);
            }
        }
        marked[v] = false;
        return paths;
    }
}

class Graph {
    private final List<Integer>[] adj;

    @SuppressWarnings("unchecked")
    Graph(int N) {
        adj = new List[N];
        for (int i = 0; i < N; i++) {
            adj[i] = new ArrayList<>();
        }
    }

    int V() {
        return adj.length;
    }

    void addEdge(int v, int w) {
        adj[v].add(w);
        adj[w].add(v);
    }

    Iterable<Integer> adj(int v) {
        return adj[v];
    }
}

class Scanner implements Closeable {
    private final InputStream stream;
    private final byte[] buf = new byte[1024];
    private int cur;
    private int num;

    Scanner(InputStream stream) {
        this.stream = stream;
    }

    int[] nextIntArray(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++)
            a[i] = nextInt();
        return a;
    }

    int nextInt() {
        return (int) nextLong();
    }

    long nextLong() {
        int c = read();
        while (isdel(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        long l = 0;
        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            l *= 10;
            l += c - '0';
            c = read();
        } while (!isdel(c));
        return l * sgn;
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }

    String next() {
        int c = read();
        while (isdel(c))
            c = read();
        StringBuilder s = new StringBuilder();
        do {
            s.appendCodePoint(c);
            c = read();
        } while (!isdel(c));
        return s.toString();
    }

    private int read() {
        if (num == -1)
            throw new InputMismatchException();
        if (cur >= num) {
            cur = 0;
            try {
                num = stream.read(buf);
            } catch (Exception e) {
                throw new InputMismatchException();
            }
            if (num <= 0)
                return -1;
        }
        return buf[cur++];
    }

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

    @Override
    public void close() {
        try {
            stream.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

Measured memory_bytes: 23636