E - Drogons in sleeping

import java.io.*;
import java.util.*;

public class E {

    final boolean ONLINE_JUDGE = true;
    BufferedReader in;
    PrintWriter out;
    StringTokenizer tok = new StringTokenizer("");

    class Graph {
        List<Integer>[] g;
        int n;
        boolean[] used;
        int[] component;
        int[] enter;
        int[] up;
        boolean[] isCutpoint;
        int time;
        int[] size;
        int[] res;

        public Graph(int n) {
            this.n = n;
            g = new List[n];
            for(int i = 0; i < n; i++) {
                g[i] = new ArrayList<Integer>();
            }
        }

        void add(int a, int b) {
            g[a].add(b);
            g[b].add(a);
        }


        int find() {
            used = new boolean[n];
            enter = new int[n];
            up = new int[n];
            isCutpoint = new boolean[n];
            component = new int[n];
            time = 0;
            dfsCutPoint(0, -1);


            Arrays.fill(used, false);
            time = -1;
            size = new int[n];
            res = new int[n];
            dfsComponent(0, -1, time);
            time++;

            int minIndex = -1;
            for(int i = 0; i < n; i++) {
                if(isCutpoint[i]) {
                    if(minIndex == -1 || res[minIndex] > res[i]) {
                        minIndex = i;
                    }
                }
            }
            if(minIndex == -1) {
                minIndex = 0;
            }
            return minIndex;
        }

        void dfsCutPoint(int v, int p) {
            used[v] = true;
            enter[v] = up[v] = time++;
            int children = 0;
            for(int to: g[v]) {
                if(to == p) continue;
                if(used[to]) {
                    up[v] = Math.min(up[v], enter[to]);
                } else {
                    children++;
                    dfsCutPoint(to, v);
                    up[v] = Math.min(up[v], up[to]);
                    if(up[to] >= enter[v]) {
                        isCutpoint[v] = true;
                    }
                }
            }
            if(v == 0) {
                isCutpoint[v] = children > 1;
            }
        }

        void dfsComponent(int v, int p, int color) {
            used[v] = true;
            size[v] = 1;
            res[v] = 0;
            int childrenSize = 0;
            for(int to: g[v]) {
                if(to == p) continue;
                if(!used[to]) {
                    if(up[to] >= enter[v]) {
                        int nextColor = ++time;
                        dfsComponent(to, v, nextColor);
                        if(res[v] < size[to]) {
                            res[v] = size[to];
                        }
                        size[v] += size[to];
                        childrenSize += size[to];
                    } else {
                        dfsComponent(to, v, color);
                        size[v] += size[to];
                    }
                }
            }
            if(res[v]  < n - childrenSize - 1) {
                res[v] = n - childrenSize - 1;
            }
        }

    }

    void solve() throws IOException {
        int n = readInt();
        int m = readInt();
        Graph g = new Graph(n);
        for(int i = 0; i < m; i++) {
            int from = readInt() - 1;
            int to = readInt() - 1;
            g.add(from, to);
        }
        int res = g.find();
        out.println((res+1));
    }


    void init() throws FileNotFoundException {
        if (ONLINE_JUDGE) {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        } else {
            in = new BufferedReader(new FileReader("input.txt"));
            out = new PrintWriter("output.txt");
        }
    }

    String readString() throws IOException {
        while (!tok.hasMoreTokens()) {
            tok = new StringTokenizer(in.readLine());
        }
        return tok.nextToken();
    }

    int readInt() throws IOException {
        return Integer.parseInt(readString());
    }

    long readLong() throws IOException {
        return Long.parseLong(readString());
    }

    double readDouble() throws IOException {
        return Double.parseDouble(readString());
    }

    int[] readArr(int n) throws IOException {
        int[] res = new int[n];
        for (int i = 0; i < n; i++) {
            res[i] = readInt();
        }
        return res;
    }

    long[] readArrL(int n) throws IOException {
        long[] res = new long[n];
        for (int i = 0; i < n; i++) {
            res[i] = readLong();
        }
        return res;
    }

    public static void main(String[] args) {
        new E().run();
    }

    public void run() {
        try {
            long t1 = System.currentTimeMillis();
            init();
            solve();
            out.close();
            long t2 = System.currentTimeMillis();
            System.err.println("Time = " + (t2 - t1));
        } catch (Exception e) {
            e.printStackTrace(System.err);
            System.exit(-1);
        }
    }
}