#include <bits/stdc++.h>
using namespace std;
const int N = 1100;
int n, m;
bool mp[N][N];
vector<int> G[N];
int tsp, cnt, dfn[N], low[N], vdcc[N], sta[N], top;
int col[N], v[N];

bool dfs(int x) {
    for (int y : G[x]) {
        if (vdcc[y] == cnt) {
            if (col[y] == -1) {
                col[y] = col[x] ^ 1;
                if (dfs(y)) return true;
            } else if (col[x] == col[y]) return true;
        }
    }
    return false;
}

void tarjan(int x) {
    dfn[x] = low[x] = ++tsp;
    sta[++top] = x;
    for (int y : G[x]) {
        if (dfn[y] == 0) {
            tarjan(y);
            low[x] = min(low[x], low[y]);
            if (dfn[x] == low[y]) {
                cnt++;
                int l = top;
                do {
                    col[sta[top]] = -1;
                    vdcc[sta[top]] = cnt;
                } while (sta[top--] != y);
                vdcc[x] = cnt;
                col[x] = 0;
                if (dfs(x)) {
                    for (int i = top + 1; i <= l; i++) v[sta[i]] = true;
                    v[x] = true;
                }
            }
        } else {
            low[x] = min(low[x], dfn[y]);
        }
    }
}

int main() {
    while (scanf("%d%d", &n, &m) != EOF) {
        if (n == 0 && m == 0) break;
        memset(mp, true, sizeof(mp));
        for (int i = 1; i <= n; i++) mp[i][i] = false;
        for (int i = 1; i <= m; i++) {
            int x, y;
            scanf("%d%d", &x, &y);
            mp[x][y] = mp[y][x] = false;
        }
        memset(G, 0, sizeof(G));
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                if (mp[i][j]) G[i].push_back(j);
            }
        }

        tsp = top = cnt = 0;
        memset(dfn, 0, sizeof(dfn));
        memset(low, 0, sizeof(low));
        memset(vdcc, 0, sizeof(vdcc));
        memset(v, false, sizeof(v));
        for (int i = 1; i <= n; i++) {
            if (dfn[i] == 0) tarjan(i);
        }

        int ans = 0;
        for (int i = 1; i <= n; i++) {
            if (!v[i]) ans++;
        }
        printf("%d\n", ans);
    }
    return 0;
}