#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9;
const ll INF=4e18;
const ll dy[8]={1,0,-1,0,0,1,-1,-1};
const ll dx[8]={0,1,0,-1,0,-1,1,-1};
template <typename T> inline bool chmax(T &a, T b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
  return ((a > b) ? (a = b, true) : (false));
}
vl seen(400010,-1);
void dfs(vvl &g,ll v,ll t){
  seen[v]=t;
  for(auto p:g[v]){
    if(seen[p]!=-1)continue;
    dfs(g,p,t);
  }
}
int main(){
  ll n,m;cin >> n >>m;
  vl pls;
  vl b(m),c(m);
  rep(i,m){
    cin >> b[i] >> c[i];
    pls.push_back(b[i]);
    pls.push_back(c[i]);
  }
  sort(all(pls));pls.erase(unique(all(pls)),pls.end());
  vvl g(pls.size());
  rep(i,m){
    ll f=lower_bound(all(pls),c[i])-pls.begin();
    ll t=lower_bound(all(pls),b[i])-pls.begin();
    g[f].push_back(t);
  }
  per(i,pls.size()){
    if(seen[i]!=-1)continue;
    dfs(g,i,i);
  }
  ll ans=n*(n+1)/2;
  //rep(i,pls.size())cout << seen[i] <<endl;
  rep(i,pls.size()){
    ans-=pls[i];
    ans+=pls[seen[i]];
  }
  cout << ans <<endl;
}