if __name__ == '__main__':
    res, ed = 0, -float('inf')
    ra = []
    n = int(input())
    for i in range(n):
        l,r = map(int,input().split())
        ra.append([r,l])
    ra.sort()

    for i in range(n):
        if ra[i][1] > ed:
            res += 1
            ed = ra[i][0]

    print(res)