#include"bits/stdc++.h" 
using namespace std; 
#ifdef ONLINE_JUDGE
#define debug(...) 42
#else
#include "puppet.h"
#endif
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
#define pb push_back
#define pob pop_back
#define bplc __builtin_popcountll 
#define bpc __builtin_popcount
#pragma GCC optimize("Ofast")
#define F first
#define S second
#define all(v) v.begin(),v.end()
#define unique(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

template<class T> using pbds= tree<T, null_type, less<T>,rb_tree_tag, tree_order_statistics_node_update>;
template<class T> using min_heap=priority_queue<T, vector<T>, greater<T>>;
// *a.find_by_order(x)-->gives xth element considering 0 indexing
// a.order_of_key(x)-->gives number of elements strictly smaller than x


// struct custom_hash {
//     static uint64_t splitmix64(uint64_t x) {
//         // http://xorshift.di.unimi.it/splitmix64.c
//         x += 0x9e3779b97f4a7c15;
//         x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
//         x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
//         return x ^ (x >> 31);
//     }
 
//     size_t operator()(uint64_t x) const {
//         static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
//         return splitmix64(x + FIXED_RANDOM);
//     }
// };


// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); 





void solve(){

int n,m;
cin>>n>>m;
vector<pair<int,int>>v(m);
for(int i=0;i<m;i++)cin>>v[i].F>>v[i].S;

sort(all(v));
int l=-2e9,r=2e9;
int ans=1;
// debug(v);
for(auto p:v){
    int L=p.F,R=p.S;
    l=max(l,L);
    r=min(r,R);
    debug(L,R);
    if(l>r){
        ans++;
        l=p.F;r=p.S;
    }
}
cout<<n-ans<<"\n";

}



int main(){ 


 ios::sync_with_stdio(0);
  cin.tie(0);


 int T=1;
//cin>>T;
while(T--){
    solve();
}



    return 0; 
}