72pts求调

#include <bits/stdc++.h>
#define IAKIOI ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
#define UPB(x, y, z) upper_bound(x + 1, x + y + 1, z) - x
#define LWB(x, y, z) lower_bound(x + 1, x + y + 1, z) - x
#define rep(i, l, r) for (int i = l; i <= r; i++)
#define pre(i, r, l) for (int i = r; i >= l; i--)
#define UNIQUE(x, y) unique(x + 1, x + y + 1)
#define SORT(x, y) sort(x + 1,x + y + 1)
#define pf push_front 
#define pb push_back 
#define IT iterator
#define lowbit(x) x & (-x)
#define re read()
#define wr(n) write(n)
#define sp putchar(' ')
#define endl puts("")

const int N = 5e5 + 10, INF = 1e9;
const double ecnts = 1e-6;

using namespace std;

#define int long long

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<int, pair<int, int> > piii;
typedef double db;

int read() {
	int f = 1, y = 0;
	char c = getchar();
	while (!isdigit(c)) {
		if (c == '-') f = -1;
		c = getchar();
	}
	while (isdigit(c)) {
		y = y * 10 + c - '0';
		c = getchar();
	}
	return y * f;
}

void write(int x) {
	if(x < 0) putchar('-'), x = -x;
	if(x > 9) write(x / 10);
	putchar(x % 10 + '0');
}

inline int max(int x, int y) {return x > y ? x : y;}
inline int min(int x, int y) {return x < y ? x : y;}

inline void swap(int &x, int &y) {int t = x;x = y, y = t;}
inline int pow(int x, int y) {
	int ans = 1;
	while (y) {
		if (y & 1) ans *= x;
		x *= x, y = y >> 1;
	}
	return ans;
}

int n, m;
vector<int> g[N];
int in[N];
bool vis[N], flag, used[N];
int F[N];
vector<int> tops;
queue<int> q;

void toposort() {
	rep(i, 1, n) {
		if (!in[i]) q.push(i);	
//		sort(g[i].begin(), g[i].end());
	}
	while (!q.empty()) {
		int u = q.front(); q.pop();
		used[u] = 1;
		for (auto v : g[u]) {
			in[v]--;
			if (!in[v]) q.push(v);
		}
	}
	rep(i, 1, n) if (!used[i]) F[i] = 1;
}

void dfs(int u, int fa, int X) {
	if (vis[u]) return ;
	vis[u] = 1;
	q.push(u);
	priority_queue<int, vector<int>, greater<int> > Q;
	for (auto v : g[u]) {
		if (v == fa || vis[v]) continue;
		Q.push(v);
	}
	while (!Q.empty()) {
		int v = Q.top();
		Q.pop();
		if (!flag && F[v] && v > X && !Q.empty()) {
			flag = 1;
			return ;
		}
		int l = 1e9;
		if (!Q.empty() && F[u]) l = -Q.top();
		dfs(v, u, l == 1e9 ? X : l);
	}
}

signed main() {
	IAKIOI
	n = re, m = re;
	rep(i, 1, m) {
		int u = re, v = re;
		g[u].push_back(v), g[v].push_back(u);
		in[u]++, in[v]++;
	}
	toposort();
	dfs(1, 1, 1e9);
	while (!q.empty()) {
		wr(q.front()), q.pop(), sp;
	}
}