#include <bits/stdc++.h>

using namespace std;

#define FOR(a, b, c) for(int a = b; a < c; a++)

const int N = 2e5+7;

vector <int> graf[N];

int dist[N];
int order[N];
int revorder[N];

int rootdist[N];

int n, m;

struct LCA
{
	vector <int> tree[N];
	int nr[N], pre[N], fir[N];
	int TIME = 0, id = 0;
	
	int sparse[2 * N][21];
	
	void dfs(int u, int p = -1)
	{
		pre[u] = TIME;
		nr[TIME] = u;
		
		sparse[id][0] = TIME++;
		fir[u] = id++;
		for (auto& v : tree[u]) if (v != p) {
			rootdist[v] = rootdist[u] + 1;
			dfs(v, u);
			sparse[id++][0] = pre[u];
		}
	}
	
	void calc() {
		dfs(0);
		for (int j = 1; (1 << j) <= id; j++)
			for (int i = 0; i + (1 << j) -1 < id; ++i) {
				sparse[i][j] = min(sparse[i][j - 1], sparse[i + (1 << (j - 1))][j - 1]);
			}
	}
	
	int minq(int l, int r) {
		int k = 31 - __builtin_clz(r - l + 1);
		return min(sparse[l][k], sparse[r - (1 << k) + 1][k]);
	}
	
	int query(int a, int b)
	{
		a = fir[a], b = fir[b];
		if (a > b) swap(a, b);
		return nr[minq(a, b)];
	}
	
	void addEdge(int a, int b)
	{
		tree[a].push_back(b);
		tree[b].push_back(a);
	}
};

LCA lca;

void bfs(int s)
{
	dist[s] = 1;
	queue <int> q;
	q.push(s);
	
	while(q.size())
	{
		auto v = q.front();
		q.pop();
		
		for (auto& u : graf[v])
		{
			if (!dist[u])
			{
				dist[u] = dist[v] + 1;
				q.push(u);
			}
		} 
	}
}

void generate_tree()
{
	vector <pair <int, int> > temp(n);
	
	for (int i = 0; i < n; ++i)
	{
		temp[i] = {dist[i], i};
	}
	
	sort(temp.begin(), temp.end());
	
	for (int i = 0; i < n; ++i)
	{
		order[i] = temp[i].second;
		revorder[temp[i].second] = order[i];	
	}
	
	for (int i = 1; i < n; ++i)
	{
		int v = order[i];
		int minn = n;
		
		for (auto& u : graf[v])
		{
			minn = min(minn, revorder[u]);
		}
			
		lca.addEdge(i, minn);
	}
}

void calcRes()
{
	lca.calc();
	long long res = 0;
	
	for (int i = 1; i < n; ++i)
	{
		res += rootdist[i - 1] + rootdist[i] - 2 * rootdist[lca.query(i - 1, i)];
	}
	
	cout << res << "\n";
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n >> m;
	
	for (int i = 0; i < m; ++i)
	{
		int a, b;
		cin >> a >> b;
		
		graf[a].push_back(b);
		graf[b].push_back(a);
	}
	
	bfs(0);
	generate_tree();
	calcRes();
}