考场上随手写的，洛谷 AC，最慢 $242ms$，但是没有任何优化，能过吗？

//18 = 9 + 9 = 18.
#include <iostream>
#include <cstdio>
#include <algorithm>
#define Debug(x) cout << #x << "=" << x << endl
using namespace std;

bool vis[10000010];
int a[770000], x[200005];

bool check(int n)
{
	while (n)
	{
		if (n % 10 == 7)
		{
			return true;
		}
		n /= 10;
	}
	return false;
}

void init(int mx)
{
	for (int i = 1; i <= mx + 100; i++)
	{
		if (check(i))
		{
			for (int j = 1; j * i <= mx + 100; j++)
			{
				vis[i * j] = true;
			}
		}
		else if (!vis[i])
		{
			a[++a[0]] = i;
		}
	}
}

int main()
{
	freopen("number.in", "r", stdin);
	freopen("number.out", "w", stdout);
	int t, mx = 0;
	scanf("%d", &t);
	for (int i = 1; i <= t; i++)
	{
		scanf("%d", x + i);
		mx = max(mx, x[i]);
	}
	init(mx);
	for (int i = 1; i <= t; i++)
	{
		if (vis[x[i]])
		{
			puts("-1");
			continue;
		}
		int id = upper_bound(a + 1, a + a[0] + 1, x[i]) - a;
		printf("%d\n", a[id]);
	}
	return 0;
}