use std::io::{read_to_string, stdin};

fn main() {
    let temp = read_to_string(stdin()).unwrap();
    let mut iter = temp
        .split_ascii_whitespace()
        .map(|x| x.parse::<i32>().unwrap());

    let n = iter.next().unwrap() as usize;

    let mut chems = (0..n)
        .map(|_| (iter.next().unwrap(), iter.next().unwrap()))
        .collect::<Vec<_>>();

    chems.sort_by_key(|x| x.1);

    let mut pin = chems[0].1;
    let mut cnt = 1;

    for (x, y) in chems {
        if x > pin {
            cnt += 1;
            pin = y;
        }
    }

    println!("{}", cnt);
}