import sys
input = sys.stdin.readline
INF = 10 ** 18

n, m = map(int,input().split())
plan = sorted([list(map(int,input().split()))[::-1] for _ in [0] * m])
now = ans = 0
for r, l in plan:
	if(now > l):
		continue
	now = r
	ans += 1
print(ans)