Submission #3422688

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
#include <string.h>
#include <iomanip>
#include <math.h>
#include <string>
#include <queue>
#include <map>
#include <set>
#include <functional>

using namespace std;

typedef long long int ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll, int> pli;
typedef std::pair<ll, ll> pll;

#define FOR(i,n,m) for(ll i=(ll)(m);i<(ll)(n);++i)
#define REP(i,n) FOR(i,n,0)
#define IREP(i,n) for(ll i=(ll)(n);i>=0;--i)
#define OF64 std::setprecision(10)

const ll MOD = 1000000007;
const ll INF = (ll)1e15;

pii B[100005];

int main()
{
	int N, M;
	cin >> N >> M;
	REP(i, M)
	{
		cin >> B[i].first >> B[i].second;
	}
	sort(B, B + M, [](pii a, pii b) {return a.second < b.second; });
	int last = -1;
	int sum = 0;
	REP(i, M)
	{
		if (B[i].first <= last)continue;
		sum++;
		last = B[i].second - 1;
	}
	cout << sum << endl;
	return 0;
}

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