#include <iostream>
#include <algorithm>
using namespace std;
int n, t[100005], len, pos;
struct mouse
{
    int w, v;
} m[100005];
bool cmp(mouse a, mouse b)
{
    if (a.v != b.v) return a.v>b.v;
    else return a.w > b.w;
}
int main()
{
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> m[i].w >> m[i].v;
    sort(m + 1, m + 1 + n, cmp);
    len = 1;
    t[1] = m[1].w;
    for (int i = 2; i <= n; i++)
    {
        if (m[i].w > t[len])
            t[++len] = m[i].w;
        else
        {
            pos = lower_bound(t + 1, t + len + 1, m[i].w) - t;
            t[pos] = m[i].w;
        }
    }
    cout << len;
    return 0;
}