#include <bits/stdc++.h>

#define maxn 1000005

using namespace std;

int n, m;
vector<int> g[maxn];

int Time;
int dfn[maxn];
int low[maxn];

int cnt;
int mn[maxn];
int col[maxn];
bool flg[maxn];

int top;
int ins[maxn];
int stk[maxn];

vector<int> ans;

void tarjan(int u) {
//	cout<<"T:"<<u<<endl; 
	dfn[u] = low[u] = ++Time;
	ins[u] = 1;
	stk[++top] = u;
	for (int v : g[u]) {
		if (!dfn[v]) {
			tarjan(v);
			low[u] = min(low[u], low[v]);
		}
		else if (ins[v]) low[u] = min(low[u], dfn[v]);
	}
	if (dfn[u] == low[u]) {
		++cnt;
		mn[cnt] = n + 1;
		while (1) {
			int v = stk[top--];
			ins[v] = 0;
			mn[cnt] = min(mn[cnt], v);
			col[v] = cnt;
			if (v == u) break;
		}
	}
}

int main() {
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= m; i++) {
		int x, y;
		scanf("%d%d", &x, &y);
		g[x].push_back(y);
	} 
	for (int i = 1; i <= n; i++) if (!dfn[i]) tarjan(i);
	
//	for (int i = 1; i <= n; i++) cout<<mn[col[i]]<<" "; puts("");
	
	for (int i = 1; i <= n; i++) {
		for (int j : g[i]) {
			if (col[i] != col[j]) flg[col[j]] = 1;
		}
	}
	for (int i = 1; i <= cnt; i++) {
		if (!flg[i]) ans.push_back(mn[i]);
	}
	sort(ans.begin(), ans.end());
	for (auto x : ans) printf("%d\n", x);
	return 0;
}