#include <vector>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;
int V, E; vector<int> G[400009], rG[400009], vs; bool used[400009]; int cmp[400009];
void add_edge(int from, int to) {
	G[from].push_back(to);
	rG[to].push_back(from);
}
void dfs(int v) {
	used[v] = true;
	for (int i = 0; i < G[v].size(); i++) {
		if (!used[G[v][i]]) dfs(G[v][i]);
	}
	vs.push_back(v);
}
void rdfs(int v, int k) {
	used[v] = true;
	cmp[v] = k;
	for (int i = 0; i < rG[v].size(); i++) {
		if (!used[rG[v][i]]) rdfs(rG[v][i], k);
	}
}
int scc() {
	fill(used, used + V, false);
	vs.clear();
	for (int v = 0; v < V; v++) {
		if (!used[v]) dfs(v);
	}
	fill(used, used + V, false);
	int k = 0;
	for (int i = vs.size() - 1; i >= 0; i--) {
		if (!used[vs[i]]) rdfs(vs[i], k++);
	}
	return k;
}
int main() {
	int N, M;
	cin >> N >> M;
	vector<int> B(M), C(M);
	for (int i = 0; i < M; ++i) {
		cin >> B[i] >> C[i];
	}
	vector<int> comp;
	for (int i = 0; i < M; ++i) {
		comp.push_back(B[i]);
		comp.push_back(C[i]);
	}
	sort(comp.begin(), comp.end());
	comp.erase(unique(comp.begin(), comp.end()), comp.end());
	int S = comp.size();
	for (int i = 0; i < M; ++i) {
		int bp = lower_bound(comp.begin(), comp.end(), B[i]) - comp.begin();
		int cp = lower_bound(comp.begin(), comp.end(), C[i]) - comp.begin();
		add_edge(bp, cp);
	}
	V = S; E = M;
	int sz = scc();
	vector<int> dp(sz);
	for (int i = 0; i < S; ++i) {
		dp[cmp[i]] = max(dp[cmp[i]], comp[i]);
	}
	vector<vector<int> > T(sz);
	for (int i = 0; i < S; ++i) {
		for (int j : G[i]) {
			if (cmp[i] != cmp[j]) {
				T[cmp[i]].push_back(cmp[j]);
			}
		}
	}
	for (int i = sz - 1; i >= 0; --i) {
		for (int j : T[i]) {
			dp[i] = max(dp[i], dp[j]);
		}
	}
	long long ans = 1LL * N * (N + 1) / 2;
	for (int i = 0; i < S; ++i) {
		ans += dp[cmp[i]] - comp[i];
	}
	cout << ans << endl;
	return 0;
}