import bisect

n = int(input())
tails = []
for _ in range(n):
    L, R = map(int, input().split())
    idx = bisect.bisect_left(tails, R)
    if idx == 0:
        x = L
        if x <= R:
            if not tails:
                tails.append(x)
            else:
                if x < tails[0]:
                    tails[0] = x
    else:
        k = idx - 1
        x = max(L, tails[k] + 1)
        if x > R:
            continue
        if idx >= len(tails):
            tails.append(x)
        else:
            if x < tails[idx]:
                tails[idx] = x
print(len(tails))