#if __has_include("../library/Basic/Debug.hpp")

#include "../library/Basic/Debug.hpp"

#else

/* ----- Header Files ----- */
// IO
#include <cstdio>
#include <iomanip>
#include <ios>
#include <iostream>

// algorithm
#include <algorithm>
#include <cmath>
#include <numeric>

// container
#include <vector>
#include <string>
#include <tuple>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>

// others
#include <random>
#include <limits>
#include <functional>
#include <ctime>
#include <cassert>
#include <cstdint>


/* ----- Type Alias ----- */
using Int = long long int;
using Real = long double;
using String = std::string;
template <class... Ts>
using Tuple = std::tuple<Ts...>;

template <class T>
using Vector = std::vector<T>;
template <class T>
using Queue = std::queue<T>;
template <class T>
using Stack = std::stack<T>;
template <class T>
using Deque = std::deque<T>;

template <class T>
using MaxHeap = std::priority_queue<T>;
template <class T>
using MinHeap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template <class T>
using Set = std::set<T>;
template <class T, class U>
using Map = std::map<T, U>;

template <class T, class... Us>
using Func = std::function<T(Us...)>;

template <class T>
T genv(T v) { return v; }

template <class T, class... Ts>
auto genv(size_t l, Ts... ts) {
    return Vector<decltype(genv<T>(ts...))>(l, Vector<T>(ts...));
}

template <class Cost = Int>
struct Edge {
    Int src, dst;
    Cost cost;
    Edge(Int src = -1, Int dst = -1, Cost cost = 1)
        : src(src), dst(dst), cost(cost){};

    bool operator<(const Edge<Cost>& e) const { return this->cost < e.cost; }
    bool operator>(const Edge<Cost>& e) const { return this->cost > e.cost; }
};

template <class Cost = Int>
using Edges = Vector<Edge<Cost>>;
template <class Cost = Int>
using Graph = Vector<Vector<Edge<Cost>>>;

#endif

/* ----- Misc ----- */
void fastio() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
}

struct Fout {
    Int precision;
    Fout(Int precision) : precision(precision) {}
};
std::ostream& operator<<(std::ostream& os, const Fout& fio) {
    os << std::fixed << std::setprecision(fio.precision);
    return os;
}


/* ----- Constants ----- */
// constexpr Int INF = std::numeric_limits<Int>::max() / 3;
// constexpr Int MOD = 1000000007;
// constexpr Real PI = acos(-1);
// constexpr Real EPS = 1e-10;
// std::mt19937 mt(int(std::time(nullptr)));

struct UnionFind {
    Vector<Int> par;
    UnionFind(Int n) : par(n) {
        std::iota(par.begin(), par.end(), 0LL);
    }

    Int find(Int v) {
        return par[v] == v ? v : par[v] = find(par[v]);
    }

    void unite(Int u, Int v) {
        u = find(u), v = find(v);
        par[v] = u;
    }
};

bool solve() {
    Int n, m;
    std::cin >> n >> m;
    if (n == 0) return false;

    UnionFind uf(n * 2);
    for (Int i = 0; i < m; ++i) {
        Int u, v;
        std::cin >> u >> v;
        --u, --v;
        uf.unite(u, v + n);
        uf.unite(u + n, v);
    }

    if (uf.find(0) == uf.find(n)) {
        std::cout << 0 << std::endl;
    } else {
        Map<Int, Int> cnt;
        for (Int v = 0; v < n; ++v) {
            Int p = uf.find(v);
            if (!cnt.count(p)) cnt[p] = 0;
            ++cnt[p];
        }

        Set<Int> ans;
        for (auto p : cnt) {
            if (p.second % 2 == 0) {
                ans.insert(p.second / 2);
            }
        }

        std::cout << ans.size() << std::endl;
        for (auto a : ans) std::cout << a << std::endl;
    }
    return true;
}

int main() {
    while (solve()) {}
    return 0;
}



Measured memory_bytes: 3084