# include <algorithm>
# include <iostream>
# include <cstring>
using namespace std;

int l[100005], r[100005], sum[5000010];
bool a[10000010];

int main()
{
	int n, l, r;
	memset(a, true, sizeof(a));
	a[1] = 0;
	a[0] = 0;
	for (int i = 2; i < 5000010; i++)
	{
		if (a[i])
		{
			for (int j = 2 * i; j < 5000010; j += i)
			{
				a[j] = false;
			}
		}
	}
	for (int i = 2; i < 5000010; i++)
	{
		if (a[i])
			sum[i] = sum[i - 1] + 1;
		else
			sum[i] = sum[i - 1];
	}
	cin >> n;
	for (int i = 1; i <= n; i++)
	{

		cin >> l >> r;
		cout << sum[r] - sum[l - 1] << endl;
	}
	return 0;
}

哪位大佬能帮我算算时间复杂度