#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>

template <class T>
std::map<T, int> compress(std::vector<T>& v) {
    std::sort(v.begin(), v.end());
    v.erase(std::unique(v.begin(), v.end()), v.end());

    std::map<T, int> rev;
    for (int i = 0; i < (int)v.size(); ++i) rev[v[i]] = i;
    return rev;
}

template <class Cost = int>
struct Edge {
    int src, dst;
    Cost cost;
    Edge(int src = -1, int dst = -1, Cost cost = 1)
        : src(src), dst(dst), cost(cost){};

    bool operator<(const Edge<Cost>& e) const { return this->cost < e.cost; }
    bool operator>(const Edge<Cost>& e) const { return this->cost > e.cost; }
};

template <class Cost = int>
struct Graph {
    std::vector<std::vector<Edge<Cost>>> graph;

    Graph(int n = 0) : graph(n) {}

    void span(bool direct, int src, int dst, Cost cost = 1) {
        graph[src].emplace_back(src, dst, cost);
        if (!direct) graph[dst].emplace_back(dst, src, cost);
    }

    int size() const { return graph.size(); }
    void clear() { graph.clear(); }
    void resize(int n) { graph.resize(n); }

    std::vector<Edge<Cost>>& operator[](int v) { return graph[v]; }
    std::vector<Edge<Cost>> operator[](int v) const { return graph[v]; }
};

using lint = long long;

void solve() {
    lint n;
    int m;
    std::cin >> n >> m;

    std::vector<std::pair<lint, lint>> es(m);
    std::vector<lint> xs;
    for (auto& [u, v] : es) {
        std::cin >> u >> v;
        xs.push_back(u);
        xs.push_back(v);
    }

    auto xrev = compress(xs);
    int nn = xs.size();

    Graph<> graph(nn);
    for (auto [u, v] : es) {
        graph.span(true, xrev[v], xrev[u]);
    }

    std::vector<lint> to(nn, -1);
    for (int i = nn - 1; i >= 0; --i) {
        if (to[i] != -1) continue;

        to[i] = xs[i];
        std::queue<int> que;
        que.push(i);

        while (!que.empty()) {
            int v = que.front();
            que.pop();

            for (auto e : graph[v]) {
                int u = e.dst;
                if (to[u] != -1) continue;
                to[u] = xs[i];
                que.push(u);
            }
        }
    }

    lint ans = n * (n + 1) / 2;
    for (int i = 0; i < nn; ++i) ans += to[i] - xs[i];
    std::cout << ans << "\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}