#include<bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pf push_front
#define LC k<<1
#define RC k<<1|1
#define IO cin.sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define all(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define rep(i, a, n) for (int i = a; i < n; i++)
#define repn(i, a, n) for (int i = a; i <= n; i++)
#define per(i, a, n) for (int i = (n) - 1; i >= a; i--)
#define pern(i, a, n) for (int i = n; i >= a; i--)

typedef long long LL;
typedef long double LD;
typedef unsigned long long ull;
typedef pair<int, int> PII;
typedef pair<int, LL> PIL;
typedef pair<LL, int> PLI;
typedef pair<double, double> PDD;
typedef pair<ull, ull> PUU;
typedef pair<LL, LL> PLL;

const int N = 1100000;
const int M = 4100000;
const int mod = 1e9+7;
const int inf = (int)1e9;
const LL INF = 1e18;
const double eps = 1e-9;

mt19937_64 Rand((unsigned long long)new char);
#define rand Rand

int f[N], num;
int find(int x) {
	return f[x] == x ? x : find(f[x]);
}
int tail, sz[N], sz2[N];
PII st[N];
void merge(int x, int y) {
	int fx = find(x), fy = find(y);
	st[++tail] = mp(fx, fy);
	if (fx != fy) {
		f[fx] = fy, sz[fy] += sz[fx], sz2[fy] += sz2[fx] + 1;
		if (sz2[fy] == sz[fy]) num++;
	}
	else {
		sz2[fx]++;
		if (sz2[fx] == sz[fx]) num++;
	}
}
vector<PII> e[M];
void insert(int k, int l, int r, int a, int b, PII c) {
	if (l == a && r == b) {
		e[k].pb(c);
		return;
	}
	int mid = (l + r) / 2;
	if (b <= mid) insert(LC, l, mid, a, b, c);
	else if (a > mid) insert(RC, mid + 1, r, a, b, c);
	else insert(LC, l, mid, a, mid, c), insert(RC, mid + 1, r, mid + 1, b, c);
}
int n, m, du[N];
vector<int> ans;
void work(int k, int l, int r) {
	int cur = tail;
	for (auto p: e[k]) {
		int x = p.fi, y = p.se;
		merge(x, y);
	}
	if (l == r) {
		if (num == 0) ans.pb(l);
	}
	else {
		int mid = (l + r) / 2;
		work(LC, l, mid);
		work(RC, mid + 1, r);
	}
	while (tail > cur) {
		auto p = st[tail--];
		int x = p.fi, y = p.se;
		if (x == y) {
			if (sz2[x] == sz[x]) num--;
			sz2[x]--;
		}
		else {
			if (sz2[y] == sz[y]) num--;
			sz2[y] -= sz2[x] + 1;
			sz[y] -= sz[x];
			f[x] = x;
		}
	}
}
int main() {
	IO;
	cin >> n >> m;
	repn(i, 1, n) f[i] = i, sz[i] = 1;
	while (m--) {
		int x, y;
		cin >> x >> y;
		du[x]++, du[y]++;
		merge(x, y);
		if (x > y) swap(x, y);
		if (x > 1) insert(1, 1, n, 1, x - 1, mp(x, y));
		if (x + 1 < y) insert(1, 1, n, x + 1, y - 1, mp(x, y));
		if (y < n) insert(1, 1, n, y + 1, n, mp(x, y));
	}
	int flag = 0;
	repn(i, 1, n) if (find(1) != find(i) || du[i] % 2 == 1) flag = 1;
	if (flag) {
		cout << "0\n";
		return 0;
	}
	repn(i, 1, n) f[i] = i, sz[i] = 1, sz2[i] = 0;
	tail = num = 0;
	work(1, 1, n);
	cout << ans.size() << "\n";
	for (auto x: ans) cout << x << " ";
	cout << "\n";
	return 0;
}