import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
sys.setrecursionlimit(10**7)
yes = lambda :print("yes");Yes = lambda :print("Yes")
no = lambda :print("no");No = lambda :print("No")
#######################################################################

n,m = na()

lr = []
for i in range(m):
    l,r = na()
    lr.append((r-1,l-1))

z = -1
lr = sorted(lr)
ans = 0
for i in range(m):
    #print(z,l,r)
    r,l = lr[i]
    if z<l:
        ans+=1
        z = r

print(n-ans)