#include <bits/stdc++.h>
using namespace std;
inline int read()//读入优化
{
    int x = 0, f = 1;
    char ch = getchar();
    while (!isdigit(ch))
    {
        f = ch != '-';
        ch = getchar();
    }
    while (isdigit(ch))
    {
        x = (x << 1) + (x << 3) + (ch ^ 48);
        ch = getchar();
    }
    return f ? x : -x;
}
inline void write(int x)//输出优化
{
    if (x >= 10)
        write(x / 10);
    putchar(x % 10 + 48);
}
const int N = 1e7 + 100;
int T, x, ls;
int f[N], nx[N];
bool check(int x)//判断是否含有数字7
{
    while (x)
    {
        if (x % 10 == 7)
            return 1;
        x /= 10;
    }
    return 0;
}
void init()//预处理部分
{
    for (int i = 1; i <= N - 10; i++)
    {
        if (f[i])//如果被标记过，就跳过
            continue;
        if (check(i))//如果含有数字7，标记其倍数
        {
            for (int j = i; j <= N - 10; j += i)
                f[j] = 1;
            continue;
        }
        nx[ls] = i;//记录i
        ls = i;//更新ls
    }
}
int main()
{
    init();//先预处理
    T = read();
    while (T--)
    {
        x = read();
        if (f[x])//被标记了输出-1，否则输出nx
            puts("-1");
        else
            write(nx[x]), putchar('\n');
    }
    return 0;
}

Goodbye OI!

#include<stdio.h>

bool yes[10001010];
int res[10001010],tot;
int x[200010],t,maxx;

bool check(int x){
	while(x){
		int t=(x%10);
		if(t==7) return 1;
		x/=10;
	}
	return 0;
}

int nxt(int x){
	for(int i=x+1;;i++){
		if(!yes[i]) return i;
	}
}

int rd(){
	int x=0,f=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-') f=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		x=(x<<1)+(x<<3)+(c^48);
		c=getchar();
	}
	return x*f;
}

int maxn(int a,int b){ return a>b?a:b; }

int main(){
	freopen("number.in","r",stdin);
	freopen("number.out","w",stdout);
	t=rd();
	for(int i=1;i<=t;i++){
		x[i]=rd();
		maxx=maxn(x[i],maxx);
	}
	for(int i=7;i<=maxx+1000;i++){
		if(!yes[i]){
			if(check(i)){
				yes[i]=1;
				res[++tot]=i;
				for(int j=i+i;j<=maxx+1000;j+=i) yes[j]=1;
			}
		}
	}
	for(int i=1;i<=t;i++){
		if(yes[x[i]]) printf("-1\n");
		else printf("%d\n",nxt(x[i]));
	}
//	fclose(stdin);
//	fclose(stdout);
	return 0;
}