import std.stdio, std.string, std.conv, std.range;
import std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, std.random, core.bitop;

void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}

void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}

bool chmin(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x > arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}

bool chmax(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x < arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}



enum inf = 1_001_001_001;
enum infl = 1_001_001_001_001_001_001L;


void main() {
    int N, M;
    scan(N, M);
    auto e = new bool[][](N, N);
    foreach (i ; 0 .. M) {
        int ai, bi;
        scan(ai, bi);
        ai--, bi--;
        e[ai][bi] = 1;
        e[bi][ai] = 1;
    }

    auto p = iota(N).array;

    int ans;

    do {
        ans += isValid(e, p);
    } while (nextPermutation(p));

    ans.writeln;
}

bool isValid(bool[][] e, int[] p) {
    if (p[0] != 0) {
        return false;
    }
    foreach (i ; 0 .. p.length.to!int - 1) {
        int u = p[i], v = p[i + 1];
        if (!e[u][v]) {
            return false;
        }
    }
    return true;
}
