n,m = map(int,input().split())
L = []
for i in range(m):
    l,r = map(int,input().split())
    L.append([r,l])
L.sort()
ans = n
r = 0
for i in range(m):
    if i <= r:
        continue
    while L[r+1][1] <= L[i][0]:
        r += 1
        if r == m-1:
            break
    ans -= 1

print(ans)