质数个数_python3

N = 1001
count = [0]*N
l = list(range(2, N))
def countP(n):
    for i in range(2, n):
        count[i] = count[i-1] + 1 if i in l else count[i-1]
        for j in range(count[i]):
            if i * l[j] >= n:
                break
            l.remove(i*l[j])
            if not i % l[j]:
                break
countP(N)
print(count[1000] - count[99])
#print(143)