#include<bits/stdc++.h>
using namespace std;
int poww(int a,int b){
	int ans = 1;
	for(int i=1;i<=b;i++){
		ans*=a;
	}
	return ans;
}
int main(){
	int n,q,minn=1000000001;
	cin>>n>>q;
	int a[n],b[q],c[q];
	for(int i=0;i<n;i++){
		cin>>a[i];
	}
	for(int i=0;i<q;i++){
		cin>>b[i]>>c[i];
		for(int j=0;j<q;j++){
			if((a[j]%poww(10,b[i]))==c[i]){
				if(a[j]<minn){
					minn=a[j];
				}
			}
		}
		if(minn==1000000001){
			cout<<-1<<endl;
		}else{
			cout<<minn<<endl;
		}
		minn=1000000001;
	}
	return 0;
}