c889

/* c889              */
/* AC (0.3s, 16.8MB) */
#include <cstdio>
#include <vector>
#include <queue>
#include <cstring>

using namespace std;

enum {undefine = -1, white, black};

int n, m, a, b, Cnt[2]{}, vex_color[100001];
vector<int> v[100001];

bool bfs(int root)
{
    if(vex_color[root] != undefine) return true;

    queue<int> q;

    int now;

    vex_color[root]=black;
    Cnt[vex_color[root]]++;

    q.emplace(root);

    while(q.size())
    {
        now = q.front(); q.pop();

        for(auto nex : v[now])
            if(vex_color[nex] == undefine)
            {
                vex_color[nex] = (vex_color[now] == black ? white : black);
                ++Cnt[vex_color[nex]];
                q.emplace(nex);
            }
            else if(vex_color[nex] == vex_color[now])
                return false;
    }
    return true;
}
int main()
{
    bool yes = true;
    int minx = 0;

    memset(vex_color, undefine, sizeof(vex_color));

    scanf("%d %d", &n, &m);

    for(int i = 0; i < m && scanf("%d %d", &a, &b); ++i)
    {
        v[a].emplace_back(b);
        v[b].emplace_back(a);
    }

    for(int i = 1; i <= n; ++i)
    {
        Cnt[0] = Cnt[1] = 0;
        yes &= bfs(i);
        minx += min(Cnt[0], Cnt[1]);
    }

    if(yes) printf("%d", minx);
    else putchar('0');

    return 0;
}