#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <string>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <iomanip>
#include <utility>
#include <tuple>
#include <functional>
#include <bitset>
#include <cassert>
#include <complex>
#include <stdio.h>
#include <time.h>
#include <numeric>
#include <random>
#include <unordered_map>
#include <unordered_set>
#define all(a) a.begin(),a.end()
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define pb push_back
#define debug(x) cerr << __LINE__ << ' ' << #x << ':' << x << '\n'
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> P;
typedef complex<ld> com;
constexpr int inf = 1000000010;
constexpr ll INF = 1000000000000000010;
constexpr ld eps = 1e-12;
constexpr ld pi = 3.141592653589793238;
template<class T, class U> inline bool chmax(T &a, const U &b) { if (a < b) { a = b; return true; } return false; }
template<class T, class U> inline bool chmin(T &a, const U &b) { if (a > b) { a = b; return true; } return false; }

map<int, int> val;

int solve(int n, map<int, vector<int>> &mp) {
	if (val.count(n)) return val[n];
	int res = n;
	for (int nxt : mp[n]) {
		chmax(res, solve(nxt, mp));
	}
	return val[n] = res;
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout << fixed << setprecision(20);

	ll n, m;
	cin >> n >> m;
	map<int, vector<int>> mp;
	vector<int> vec;
	rep(i, m) {
		int b, c;
		cin >> b >> c;
		if (b < c) {
			mp[b].pb(c);
			vec.pb(b);
		}
	}
	for (int i : vec) solve(i, mp);
	ll ans = n * (n + 1) / 2;
	for (auto i : val) {
		ll x = i.first; ll y = i.second;
		ans += y - x;
	}
	cout << ans << '\n';
}