/*
Solution for Season 6 Round 6 Problem 3 Senior
Author: Anton Chernev
*/

#include <cstdio>
#include <vector>
#include <algorithm>
#include <stack>

using std::vector;
using std::min;
using std::stack;

const int MAX_N = 100001;

int N, M;
vector<int> edges[MAX_N];
stack<int> processed;
int label[MAX_N], minReachable[MAX_N], nextLabel;
bool isProcessed[MAX_N], suitable[MAX_N];

void read()
{
    int x, y;

    scanf("%d%d", &N, &M);

    for(size_t i = 0; i < M; ++i)
    {
        scanf("%d%d", &x, &y);
        edges[x].push_back(y);

        if(x == y) suitable[x] = true;
    }
}

int dfs(int vertex)
{
    label[vertex] = minReachable[vertex] = nextLabel++;
    processed.push(vertex);
    isProcessed[vertex] = true;

    for(size_t i = 0; i < edges[vertex].size(); i++)
        if(label[edges[vertex][i]])
        {
            if(isProcessed[edges[vertex][i]])
                minReachable[vertex] = min(minReachable[vertex], minReachable[edges[vertex][i]]);
        }
        else
            minReachable[vertex] = min(minReachable[vertex], dfs(edges[vertex][i]));

    if(minReachable[vertex] == label[vertex])
    {
        if(processed.top() != vertex)
            suitable[vertex] = true;

        while(processed.top() != vertex)
        {
            isProcessed[processed.top()] = false;
            processed.pop();
        }
        isProcessed[vertex] = false;
        processed.pop();
    }
    else suitable[vertex] = true;

    return minReachable[vertex];
}

void print()
{
    for(size_t i = 1; i <= N; ++i)
        if(suitable[i]) printf("%d\n", i);
}

int main()
{
    freopen("tourism.in", "r", stdin);
    freopen("tourism.out", "w", stdout);

    read();

    nextLabel = 1;
    for(size_t i = 1; i <= N; ++i)
        if(!label[i]) dfs(i);

    print();
}
/*

*/