//icebreaker.cpp
#include<cstdio> 
#include<cstring>
#include<vector>
using namespace std;
const int maxn = 10000 + 5;

int n, m;
vector<int> g[maxn];
int label[maxn];

bool dfs(const vector<int> g[maxn], int label[maxn], int u, int tag, int &cnt0, int &cnt1)
{
	label[u] = tag;
	if (tag == -1)
	{
		++cnt0;
	}
	else
	{
		++cnt1;
	}
	
	for (const int &v : g[u])
	{
		if (label[v] == tag)
		{
			return false;
		}
		else if (label[v] == 0 && dfs(g, label, v, -tag, cnt0, cnt1) == false)
		{
			return false;
		}
	}
	return true;
}

int main()
{
	int ret = 0;
	scanf("%d%d", &n, &m);
	memset(label, 0, sizeof(label));
	for (int i = 0; i < m; ++i)
	{
		int u, v;
		scanf("%d%d", &u, &v);
		g[u].emplace_back(v);
		g[v].emplace_back(u);
	}
	for (int i = 1; i <= n; ++i)
	{
		int cnt0 = 0, cnt1 = 0;
		if (label[i] == 0)
		{
			if(dfs(g, label, i, 1, cnt0, cnt1) == false)
			{
				ret = 0;
				break;
			}
			ret += max(cnt0, cnt1);
		}
	}
	printf("%d\n", ret);
	return 0;
}