#include<bits/stdc++.h>
using namespace std;
int n,m,a[1000],p,q,k[8],minn;
int main()
{
    k[1]=10;
    for (int i=2;i<=7;i++)
    {
        k[i]=k[i-1]*10;
    }
    cin>>n>>m;
    for (int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    for (int i=1;i<=m;i++)
    {
        minn=0x7fffffff;
        cin>>p>>q;
        for (int j=1;j<=n;j++)
        {
            if ((a[j]%k[p])==q)
            {
                minn=min(minn,a[j]);
            }
        }
        if (minn==0x7fffffff)
        {
            cout<<-1<<endl;
        }
        else
        {
            cout<<minn<<endl;
        }
    }
    return 0;
}