third silver usaco Jan 14

#include <iostream>
#include <vector>
#include <fstream>
#include <algorithm>
#include <iomanip>
#include <map>
#include <queue>
#include <stack>
#include <set>
#include <ctime>
#include <iterator>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <limits.h>
using namespace std;


int main()
{
    ifstream in("recording.in");
    ofstream out("recording.out");
    #define cin in
    #define cout out
    int nb_programmes;
    cin>>nb_programmes;
    vector<pair<int,int> > intervalles(nb_programmes);
    for(int c=0;c<nb_programmes;c++)
    {
        cin>>intervalles[c].second>>intervalles[c].first;
    }
    sort(intervalles.begin(),intervalles.end());
    int busy[2]={0,0};
    int res = 0;
    for(int c=0;c<intervalles.size();c++)
    {
        int c2 = 0;
        for(c2=0;c2<2&&intervalles[c].second<busy[c2];c2++);
        if(c2==2) continue;
        res++;
        busy[c2]=intervalles[c].first;
        if(busy[1]>busy[0]) swap(busy[1],busy[0]);
    }
    cout<<res<<endl;
}