#include <bits/stdc++.h>

#define M_PI       3.14159265358979323846   // pi

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;

#define rep(a,n) for(ll a = 0;a < n;a++)
#define repi(a,n) for(ll a = n - 1;a >= 0;a--)

template<typename T>
void chmax(T& reference, T value) {
    reference = max(reference, value);
}

template<typename T>
void chmaxmap(map<T, T>& m, T key, T value) {
    if (m.count(key)) {
        chmax(m[key], value);
    }
    else {
        m[key] = value;
    }
}

template<typename T>
void chmin(T& reference, T value) {
    reference = min(reference, value);
}

#include <atcoder/all>

using namespace atcoder;

typedef modint1000000007 mint;

constexpr ll mod = 1000000007;

constexpr ll mpow(ll x, ll n) {
    ll ans = 1; x %= mod;
    while (n != 0) {
        if (n & 1) ans = ans * x % mod;
        x = x * x % mod;
        n = n >> 1;
    }
    return ans;
}

class Primes {
private:
	vector<int> Prime_Number;
	vector<bool> is_prime_;
public:
	Primes(int N) {
		is_prime_.resize(N + 1, true);
		is_prime_[0] = is_prime_[1] = false;
		for (int i = 0; i < N + 1; i++) {
			if (is_prime_[i]) {
				Prime_Number.push_back(i);
				for (int j = 2 * i; j <= N; j += i) is_prime_[j] = false;
			}
		}
	}
	int operator[](int i) { return Prime_Number[i]; }
	int size() { return Prime_Number.size(); }
	int back() { return Prime_Number.back(); }
	bool isPrime(int q) { return is_prime_[q]; }
};

class SDivisor {
public:
	vector<ll> F;

	SDivisor(ll N) {
		for (ll i = 1; i * i <= N; i++) {
			if (N % i == 0) {
				F.push_back(i);
				if (i * i != N) F.push_back(N / i);
			}
		}
		sort(begin(F), end(F));
	}
	int size() { return F.size(); }
	ll operator[](int k) { return F[k]; }
	const vector<ll>& factors() { return F; }
};

class Divisor {
private:
	vector<ll> F;
	vector<pair<ll, ll>> pfactorize;
public:
	Divisor(ll N) {
		for (ll i = 1; i * i <= N; i++) {
			if (N % i == 0) {
				F.push_back(i);
				if (i * i != N) F.push_back(N / i);
			}
		}
		sort(begin(F), end(F));
		Primes p((ll)sqrt(N) + 1);
		for (int i = 0; i < p.size(); i++) {
			pfactorize.emplace_back(p[i], 0);
			while (N % p[i] == 0) {
				N /= p[i];
				pfactorize.back().second++;
			}
			if (pfactorize.back().second == 0) pfactorize.pop_back();
		}
		if (N > 1) pfactorize.emplace_back(N, 1);
	}
	int size() { return F.size(); }
	const vector<pair<ll, ll>>& pfac() { return pfactorize; }
	ll operator[](int k) { return F[k]; }
	const vector<ll>& factors() { return F; }
};


int main() {
	ll n, m;
	cin >> n >> m;
	map<ll, vector<ll>> es;
	vector<bool> visit(m + 10, false);
	rep(i, m) {
		ll l, r;
		cin >> l >> r;
		es[l].push_back(- i - 1);
		es[r].push_back(i + 1);
	}
	vector<ll> ids;
	ll ans = 0;
	for (auto& x : es) {
		ll key = x.first;
		vector<ll> any;
		for (auto y : x.second) {
			ll id = abs(y);
			int enter = y < 0;
			if (enter) {
				if (visit[id]) continue;
				ids.push_back(id);
			}
			else {
				if (visit[id]) continue;
				any.push_back(id);
			}
		}
		if (any.size()) {
			ans++;
			for (auto a : ids) visit[a] = 1;
			ids.clear();
		}
	}
	cout << n - ans << endl;
    return 0;
}