#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
map<int, vector<int>> g;
map<int, bool> vis;
map<int, int> to;
int dfs (int cur) {
  if (vis[cur]) return to[cur];
  vis[cur] = true;
  int res = cur;
  for (int& nxt : g[cur]) {
    res = max(res, dfs(nxt));
  }
  return to[cur] = res;
}
signed main() { 
  ios::sync_with_stdio(false); cin.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    g[a].push_back(b);
  }
  long long ans = 1LL * n * (n + 1) / 2;
  for (auto& p : g) {
    int get = dfs(p.first);
    ans += get - p.first;
  }
  cout << ans << endl;
  return 0;
}