/* -*- coding: utf-8 -*-
 *
 * 1194.cc:  No.1194 Replace - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_M = 200000;
const int MAX_K = MAX_M * 2;

/* typedef */

typedef long long ll;
typedef vector<int> vi;
typedef queue<int> qi;
typedef pair<int,int> pii;

/* global variables */

pii es[MAX_M];
int uvs[MAX_K], mxs[MAX_K];
vi nbrs[MAX_K];

/* subroutines */

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);

  int k = 0;
  for (int i = 0; i < m; i++) {
    int b, c;
    scanf("%d%d", &b, &c);
    es[i] = pii(b, c);
    uvs[k++] = b, uvs[k++] = c;
  }

  sort(uvs, uvs + k);
  k = unique(uvs, uvs + k) - uvs;
  //printf("k=%d\n", k);

  for (int i = 0; i < m; i++) {
    int bi = lower_bound(uvs, uvs + k, es[i].first) - uvs;
    int ci = lower_bound(uvs, uvs + k, es[i].second) - uvs;
    nbrs[ci].push_back(bi);
  }

  for (int st = k - 1; st >= 0; st--)
    if (! mxs[st]) {
      int x = mxs[st] = uvs[st];
      qi q;
      q.push(st);

      while (! q.empty()) {
	int u = q.front(); q.pop();
	vi &nbru = nbrs[u];
	for (vi::iterator vit = nbru.begin(); vit != nbru.end(); vit++) {
	  int v = *vit;
	  if (! mxs[v]) {
	    mxs[v] = x;
	    q.push(v);
	  }
	}
      }
    }

  ll sum = (ll)n * (n + 1) / 2;
  for (int i = 0; i < k; i++)
    sum += mxs[i] - uvs[i];

  printf("%lld\n", sum);
  return 0;
}