#include <bits/stdc++.h>
using namespace std;
#define modulo 998244353
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 1000000005


int main(){
	
	int N,M;
	cin>>N>>M;
	
	vector<int> B(M),C(M);
	vector<int> t;
	for(int i=0;i<M;i++){
		cin>>B[i]>>C[i];
		
		t.push_back(B[i]);
		t.push_back(C[i]);
	}
	
	sort(t.begin(),t.end());
	t.erase(unique(t.begin(),t.end()),t.end());
	vector<vector<int>> E(t.size(),vector<int>());
	for(int i=0;i<M;i++){
		B[i] = distance(t.begin(),lower_bound(t.begin(),t.end(),B[i]));
		C[i] = distance(t.begin(),lower_bound(t.begin(),t.end(),C[i]));
		E[C[i]].push_back(B[i]);
	}
	
	vector<int> dis(t.size());
	priority_queue<pair<int,int>> Q;
	
	for(int i=0;i<t.size();i++){
		dis[i] = t[i];
		Q.emplace(t[i],i);
	}
	
	while(Q.size()!=0){
		int D = Q.top().first;
		int u = Q.top().second;
		Q.pop();
		
		if(dis[u]!=D)continue;
		
		for(int i=0;i<E[u].size();i++){
			int v = E[u][i];
			if(dis[v]<D){
				dis[v] = D;
				Q.emplace(dis[v],v);
			}
		}
	}
	
	long long ans = (long long)N*(N+1)/2;
	
	for(int i=0;i<t.size();i++){
		ans -= t[i];
		ans += dis[i];
	}
	
	cout<<ans<<endl;
	
	return 0;
}