#include <fstream>
#include <algorithm>

using namespace std;

ifstream fin ("pachete.in");
ofstream fout ("pachete.out");

struct client
{
    int x,y;
}v[50001];
int n,s[50001],l;

bool cmp (client a, client b)
{
    return a.x < b.x;
}

int bs (int x)
{
    int lo = -1, hi = l+1;

    while (hi - lo > 1)
    {
        int mid = (lo + hi)/2;

        if (x < s[mid])
          lo = mid;
        else hi = mid;
    }

    return hi;
}

int main()
{
    fin>>n;

    for (int i=1; i<=n; ++i)
    {
        fin>>v[i].x>>v[i].y;
    }

    sort (v+1,v+n+1,cmp);

    s[0] = 2000000001;

    for (int i=1; i<=n; ++i)
    {
        int pos = bs (v[i].y);

        if (pos == l+1)
            ++l;
        s[pos] = v[i].y;
    }

    fout<<l;
}