#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef long double ld;
typedef complex<double> comp;
const ll inf=1e9+7;
const ll mod=998244353;
const int MAX=300010;


signed main(){
    ll n,m;cin>>n>>m;
    map<ll,ll>idx;
    vector<ll>inv(2*m);
    map<ll,ll>con;
    vector<vector<ll> >G(2*m);
    ll now=0;
    vector<ll>q(m);
    rep(i,m){
        ll b,c;cin>>b>>c; 
        con[b]=b;
        con[c]=c;
        q[i]=c;
        if(idx.find(c)==idx.end()){
            idx[c]=now;
            now++;
        }
        if(idx.find(b)==idx.end()){
            idx[b]=now;
            now++;
        }
        inv[idx[c]]=c;
        inv[idx[b]]=b;
        G[idx[c]].pb(idx[b]);
    }
    sort(rall(q));
    vector<ll>used(2*m);
    rep(i,m){
        if(used[idx[q[i]]])continue;
        ll c=q[i];
        queue<ll>q;
        used[idx[c]]=1;
        q.push(idx[c]);
        while(!q.empty()){
            ll k=q.front();
            q.pop();
            //cout<<inv[k]<<' '<<c<<endl;
            for(auto e:G[k]){
                if(used[e])continue;
                con[inv[e]]=max(con[inv[e]],c);
                used[e]=1;
                q.push(e);
            }
        }
    }
    ll ans=n*(n+1)/2;
    for(auto e:con){
        ans+=e.se-e.fi;
    }
    cout<<ans<<endl;
}