代码示例：
frommathimportsqrt
defis_prime(n):
ifn==1:
returnFalse
foriinrange(2,int(sqrt(n))+1):
ifn%i==0:
returnTrue
count=0
foriinrange(1,1000):
ifis_prime(i):
count=count+1
print('{}:{}'.format(count,i))
