import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Set;
import java.util.HashSet;

public class Main {
    static int ans = 0;
    static boolean[][] matrix;
    static int[] input;

    public static void main(String[] args) throws IOException {
        try (InputReader reader = new InputReader(System.in)) {
            solve(reader);
        }
    }

    private static void solve(InputReader reader) throws IOException {
        input = reader.readIntsSplitByDelimiter(" ");
        matrix = new boolean[input[0]][input[0]];
        for (int i = 0; i < input[1]; i++) {
            int[] input2 = reader.readIntsSplitByDelimiter(" ");
            matrix[input2[0] - 1][input2[1] - 1] = true;
            matrix[input2[1] - 1][input2[0] - 1] = true;
        }

        Set<Integer> visitedSet = new HashSet<>(input[0]);
        dfs(0, new HashSet<Integer>(visitedSet));
        System.out.println(ans);
    }

    static void dfs(int position, Set<Integer> visitedSet) {
        visitedSet.add(position);
        if (visitedSet.size() == input[0]) {
            ans++;
            return;
        }

        for (int i = 0; i < input[0]; i++) {
            if (visitedSet.contains(i) == false && matrix[position][i] == true) {
                dfs(i, new HashSet<Integer>(visitedSet));
            }
        }

        return;
    }
}

class Util {
    static int gcd(int m, int n) {
        int min = Math.min(m, n);
        int max = Math.max(m, n);
        while (min != 0) {
            int tmp = min;
            min = max % tmp;
            max = tmp;
        }

        return max;
    }
}

class InputReader implements Closeable, AutoCloseable {
    private final BufferedReader br;

    InputReader(InputStream inputStream) {
        this.br = new BufferedReader(new InputStreamReader(inputStream));
    }

    String readLine() throws IOException {
        return this.br.readLine();
    }

    int readInt() throws IOException {
        return Integer.parseInt(this.readLine());
    }

    long readLong() throws IOException {
        return Long.parseLong(this.readLine());
    }

    double readDouble() throws IOException {
        return Double.parseDouble(this.readLine());
    }

    String[] readStringsSplitByDelimiter(String delimiter) throws IOException {
        return this.readLine().split(delimiter);
    }

    int[] readIntsSplitByDelimiter(String delimiter) throws IOException {
        String[] strings = this.readStringsSplitByDelimiter(delimiter);

        int stringsLength = strings.length;
        int[] ints = new int[stringsLength];
        for (int i = 0; i < stringsLength; i++) {
            ints[i] = Integer.parseInt(strings[i]);
        }

        return ints;
    }

    long[] readLongsSplitByDelimiter(String delimiter) throws IOException {
        String[] strings = this.readStringsSplitByDelimiter(delimiter);

        int stringsLength = strings.length;
        long[] longs = new long[stringsLength];
        for (int i = 0; i < stringsLength; i++) {
            longs[i] = Long.parseLong(strings[i]);
        }

        return longs;
    }

    double[] readDoublesSplitByDelimiter(String delimiter) throws IOException {
        String[] strings = this.readStringsSplitByDelimiter(delimiter);

        int stringsLength = strings.length;
        double[] doubles = new double[stringsLength];
        for (int i = 0; i < stringsLength; i++) {
            doubles[i] = Double.parseDouble(strings[i]);
        }

        return doubles;
    }

    @Override
    public void close() throws IOException {
        this.br.close();
    }
}


Measured memory_bytes: 26680