[NOIP2017]图书管理员 (nowcoder.com)
 

#include<bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
const int N =2e5+10,M=1e3+10;
int a[N];
int n,q;
int check(int l,int x)
{
	int tmp=pow(10,l);
	for(int i=1;i<=n;i++)
	{
		if(a[i]%tmp==x)
		{
			cout<<a[i]<<endl;
			return 0;
		}
	}
	cout<<-1<<endl;
	return 0;
}
signed main()
{
    std::ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
   	cin>>n>>q;
   	for(int i=1;i<=n;i++)cin>>a[i];//book bianma
    sort(a+1,a+1+n);
    while(q--)
    {
    	int l,x;cin>>l>>x;
    	check(l,x);
	}
    return 0;
}