#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>

using namespace std;

const int MAXN = 2e5 + 5;

typedef pair <int, int> PII;

int n, f[MAXN];
PII q[MAXN];

int main(){
    scanf("%d", &n);
    for(int i = 0; i < n; i++){
        scanf("%d%d", &q[i].first, &q[i].second);
    }
    sort(q, q + n);
    int res = 0;
    for(int i = 0; i < n; i++){
        f[i] = 1;
        for(int j = 0; j < i; j++){
            if(q[i].second > q[j].second){
                f[i] = max(f[i], f[j] + 1);
            }
        }
        res = max(res, f[i]);
    }
    printf("%d", res);
    return 0;
}