#include <stdio.h>
#define R 411
#define C 611

double t[R][C];
int basis[C];

int main() {
    int n, m;
    scanf("%d%d", &n, &m);
    // fill up table
    for (int i = 0; i < n; i++) {
        t[0][i] = -1;
    }
    for (int i = 1; i <= m; i++) {
        int a, b;
        scanf("%d%d", &a, &b);
        a--, b--;
        t[i][a] = t[i][b] = t[i][n + i - 1] = 1;
        t[i][n + m] = 1;
        basis[n + i - 1] = i;
    }
    while (true) {
        int J = -1;
        for (int j = 0; j < n + m; j++) {
            if (!basis[j] && t[0][j] < 0) {
                J = j;
                break;
            }
        }
        if (!~J) break;
        // pivot on J
        double minim = 1e111;
        int I = 0;
        for (int i = 1; i <= m; i++) {
            if (t[i][J] <= 0) continue;
            double quot = t[i][n+m] / t[i][J];
            if (minim > quot) {
                minim = quot;
                I = i;
            }
        }
        if (I == 0) {
            // singleton vertex... ignore
            t[0][n+m] -= t[0][J];
            t[0][J] = 0;
            continue;
        }
        // pivot on I
        double sc = t[I][J];
        for (int j = 0; j <= n + m; j++) {
            t[I][j] /= sc;
        }
        for (int i = 0; i <= m; i++) {
            if (i == I) continue;
            sc = t[i][J];
            for (int j = 0; j <= n + m; j++) {
                t[i][j] -= t[I][j] * sc;
            }
        }
        for (int j = 0; j < n + m; j++) {
            if (basis[j] == I) {
                basis[j] = 0;
                break;
            }
        }
        basis[J] = I;
    }


    // 2*result - n
    double ans = 2*t[0][n+m] - n;
    printf("%.0lf\n", ans);

}