import sys
readline = sys.stdin.readline

N, M = map(int, readline().split())
D = []
for i in range(M):
    L, R = map(int, readline().split())
    D.append((L, R))
D.sort(reverse=True)

ans = N
pre = 10 ** 18
for i in range(M):
    L, R = D[i]
    if R >= pre:
        continue
    else:
        ans -= 1
        pre = L
print(ans)