N,M = map(int,input().split())
LR = [list(map(int,input().split())) for _ in range(M)]
LR.sort()
LR.append([10**9+1,10**9+2])
cnt = 0
lc = 0
rmin = 10**10
for l,r in LR:
    if lc < l:
        lc = l
        rmin = min(r,rmin)
        if l > rmin:
            cnt += 1
            rmin = r
print(N-cnt)