// nemesGyak000.cpp : This file contains the 'main' function. Program execution begins and ends there.
//
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
int length, q;
cin >> length >> q;
vector<pair<int, int>> times;
for (size_t i = 0; i < q; i++)
{
int p, n;
cin >> p >> n;
times.push_back({p,1});
times.push_back({n,-1 });
}
sort(times.begin(), times.end());
int Index = 1;
int SUM = 0;
int rn = 0;
int beginning = -1;
if (times[0].first != 1) rn++;
for (size_t i = 0; i < times.size(); i++)
{
SUM += times[i].second;
if (times[i].first!=length) {
if (beginning == times[i].first) {
rn--;
beginning = -1;
}
if (SUM == 0) {
rn++;
beginning = times[i].first;
}
}
}
cout << rn << "\n";
}
// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu
// Tips for Getting Started:
// 1. Use the Solution Explorer window to add/manage files
// 2. Use the Team Explorer window to connect to source control
// 3. Use the Output window to see build output and other messages
// 4. Use the Error List window to view errors
// 5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
// 6. In the future, to open this project again, go to File > Open > Project and select the .sln file