import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;

public class Main {

    private static void reverse(int[] a, int fromIndex, int toIndex) {
        assert fromIndex >= 0 : fromIndex;
        assert toIndex <= a.length : "to=" + toIndex + ", len=" + a.length;
        assert fromIndex <= toIndex : "from=" + fromIndex + ", to=" + toIndex;

        for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) {
            int tmp = a[i];
            a[i] = a[j];
            a[j] = tmp;
        }
    }

    private static boolean nextPermutation(int[] a) {
        assert a.length <= 10 : a.length;

        int i = a.length - 2;
        while (i >= 0 && a[i] >= a[i + 1]) {
            i--;
        }
        if (i < 0) {
            return false;
        }
        int j = a.length - 1;
        while (a[i] >= a[j]) {
            j--;
        }
        int tmp = a[i];
        a[i] = a[j];
        a[j] = tmp;
        reverse(a, i + 1, a.length);
        return true;
    }

    static void exec(MyScanner in, PrintWriter out) {
        int N = in.nextInt();
        int M = in.nextInt();
        int[] a = new int[M];
        int[] b = new int[M];
        in.nextVerticalIntArrays(a, b);
        boolean[][] m = new boolean[N][N];
        for (int i = 0; i < M; i++) {
            m[a[i] - 1][b[i] - 1] = true;
            m[b[i] - 1][a[i] - 1] = true;
        }
        int[] p = new int[N - 1];
        for (int i = 0; i < N - 1; i++) {
            p[i] = i + 1;
        }
        int ans = 0;
        label : do {
            int prev = 0;
            for (int v : p) {
                if (!m[prev][v]) {
                    continue label;
                }
                prev = v;
            }
            ans++;
        } while (nextPermutation(p));
        out.println(ans);
    }

    public static void main(String[] args) {
        PrintWriter w = new PrintWriter(System.out);
        exec(new MyScanner(System.in), w);
        w.flush();
    }

    static final class MyScanner {
        static final int BUFFER_SIZE = 8192;
        private final InputStream in;
        private final byte[] buffer = new byte[BUFFER_SIZE];
        private int point;
        private int readLength;
        MyScanner(InputStream in) {
            this.in = in;
        }
        private int readByte() {
            if (point < readLength) {
                int result = buffer[point];
                point += 1;
                return result;
            }
            try {
                readLength = in.read(buffer);
            } catch (IOException e) {
                throw new AssertionError(null, e);
            }
            if (readLength == -1) {
                return -1;
            }
            point = 1;
            return buffer[0];
        }
        private static boolean isPrintableCharExceptSpace(int c) {
            return 33 <= c && c <= 126;
        }
        String next() {
            int c = readByte();
            while (!(c == -1 || isPrintableCharExceptSpace(c))) {
                c = readByte();
            }
            assert c != -1;
            StringBuilder b = new StringBuilder();
            do {
                b.appendCodePoint(c);
                c = readByte();
            } while (c != -1 && isPrintableCharExceptSpace(c));
            return b.toString();
        }
        long nextLong() {
            int c = readByte();
            while (!(c == -1 || isPrintableCharExceptSpace(c))) {
                c = readByte();
            }
            assert c != -1;
            boolean minus = false;
            if (c == '-') {
                minus = true;
                c = readByte();
            }
            long result = 0L;
            do {
                assert '0' <= c && c <= '9' : c;
                result = result * 10L + (c - '0');
                c = readByte();
            } while (c != -1 && isPrintableCharExceptSpace(c));
            return minus ? -result : result;
        }
        int nextInt() {
            long n = nextLong();
            assert Integer.MIN_VALUE <= n && n <= Integer.MAX_VALUE : n;
            return (int)n;
        }
        double nextDouble() {
            return Double.parseDouble(next());
        }
        int[] nextIntArray(int n) {
            int[] result = new int[n];
            for (int i = 0; i < n; i++) {
                result[i] = nextInt();
            }
            return result;
        }
        private static boolean allSameLength(int[] a, int[] b, int[]... c) {
            if (a.length != b.length) {
                return false;
            }
            for (int i = 0; i < c.length; i++) {
                if (a.length != c[i].length) {
                    return false;
                }
            }
            return true;
        }
        private static boolean allSameLength(char[] a, char[] b, char[]... c) {
            if (a.length != b.length) {
                return false;
            }
            for (int i = 0; i < c.length; i++) {
                if (a.length != c[i].length) {
                    return false;
                }
            }
            return true;
        }
        void nextVerticalIntArrays(int[] a, int[] b, int[]... c) {
            assert allSameLength(a, b, c);
            for (int i = 0; i < a.length; i++) {
                a[i] = nextInt();
                b[i] = nextInt();
                for (int[] d : c) {
                    d[i] = nextInt();
                }
            }
        }
        long[] nextLongArray(int n) {
            long[] result = new long[n];
            for (int i = 0; i < n; i++) {
                result[i] = nextLong();
            }
            return result;
        }
        char nextChar() {
            int c = readByte();
            while (!(c == -1 || isPrintableCharExceptSpace(c))) {
                c = readByte();
            }
            assert c != -1;
            return (char)c;
        }
        char[] nextCharArray(int n) {
            char[] result = new char[n];
            for (int i = 0; i < n; i++) {
                result[i] = nextChar();
            }
            return result;
        }
        char[][] next2dCharArray(int n, int m) {
            char[][] result = new char[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    result[i][j] = nextChar();
                }
            }
            return result;
        }
        void nextVerticalCharArrays(char[] a, char[] b, char[]... c) {
            assert allSameLength(a, b, c);
            for (int i = 0; i < a.length; i++) {
                a[i] = nextChar();
                b[i] = nextChar();
                for (char[] d : c) {
                    d[i] = nextChar();
                }
            }
        }
    }
}


Measured memory_bytes: 22356