1.筛选质数时用线性筛法（欧拉筛），传统 $O(n\sqrt{n})$ 筛法：

bool prime(int n)
{
	if(n==0||n==1) return false;
	if(n==2) return true;
	for(int i=2;i*i<=n;i++)
		if(n%i==0) return false;
	return true;
}

TLE 60pts

2.for循环中pow函数要在外部写，不然pow反复调用费时间。

3.打表dafa好：

int a[10][100]={{},{2,3,5,7},
{23,29,31,37,53,59,71,73,79},
{233,239,293,311,313,317,373,379,593,599,719,733,739,797},
{2333,2339,2393,2399,2939,3119,3137,3733,3739,3793,3797,5939,7193,7331,7333,7393},
{23333,23339,23399,23993,29399,31193,31379,37337,37339,37397,59393,59399,71933,73331,73939},
{233993,239933,293999,373379,373393,593933,593993,719333,739391,739393,739397,739399},
{2339933,2399333,2939999,3733799,5939333,7393913,7393931,7393933},
{23399339,29399999,37337999,59393339,73939133}};

（死了