#include <vector>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;
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());
	vector<vector<int> > G(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();
		G[bp].push_back(cp);
	}
	vector<bool> vis(comp.size(), false);
	vector<int> dp(comp.size());
	function<int(int)> dfs = [&](int pos) {
		vis[pos] = true;
		int res = pos;
		for (int i : G[pos]) {
			if (vis[i]) {
				res = max(res, dp[i]);
			}
			else {
				res = max(res, dfs(i));
			}
		}
		dp[pos] = res;
		return res;
	};
	for (int i = 0; i < comp.size(); ++i) {
		vis = vector<bool>(comp.size(), false);
		dfs(i);
	}
	long long ans = 1LL * N * (N + 1) / 2;
	for (int i = 0; i < comp.size(); ++i) {
		ans += comp[dp[i]] - comp[i];
	}
	cout << ans << endl;
	return 0;
}