#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>

using namespace std;
typedef long long ll;

ll N, M;
map<ll, vector<ll>> G;
set<ll> used;
ll ans;

bool is_used(ll m){
    return used.count(m) > 0;
}

void dfs(ll v, ll r){
    used.insert(v);
    if(r > v) ans += r-v;
    for(ll to : G[v]){
        if(!is_used(to)) dfs(to, r);
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    cin >> N >> M;
    vector<ll> v;
    for(int i = 0; i < M; i++){
        ll b, c; cin >> b >> c;
        G[c].push_back(b);
        v.push_back(c);
    }
    ans = (N*(N+1))/2;
    sort(v.begin(), v.end(), greater<ll>());
    for(ll i : v) {
        if(!is_used(i)) dfs(i, i);
    }
    cout << ans << endl;
}