#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;
    vector<pll>q(m);
    map<ll,ll>ma;
    rep(i,m){
        ll b,c;cin>>b>>c;
        ma[b]=b;
        ma[c]=c;
        q[i]=mp(c,b);
    }
    sort(rall(q));
    rep(i,m){
        ll b=q[i].second;
        ll c=q[i].first;
        ma[b]=max(ma[b],ma[c]);
    }
    ll ans=n*(n+1)/2;
    for(auto e:ma){
        ll b=e.fi;
        ll c=e.se;
        ans+=(c-b);
    }
    cout<<ans<<endl;
}