# import sys
# input = sys.stdin.readline
def mp():return map(int,input().split())
def lmp():return list(map(int,input().split()))
import math
import bisect
from copy import deepcopy as dc
from itertools import accumulate
from collections import Counter, defaultdict, deque
def ceil(U,V):return (U+V-1)//V
def modf1(N,MOD):return (N-1)%MOD+1
inf = int(1e30)
mod = int(1e9+7)

n,m = mp()
h = []
for i in range(m):
    a,b = mp()
    h.append((a,b))
h.sort(key=lambda x:x[1])
bot = 0
for i,j in h:
    if bot < i:
        n -= 1
        bot = j
print(n)