Java :

import java.util.Scanner;

public class Main {
	
	static char a[][] = new char[1001][1001];
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int book[] = new int[1001];
		int len[] = new int[1001];
		int num[] = new int[1001];

		int n = sc.nextInt();
		int q = sc.nextInt();
				
		for(int i=1;i<=n;i++){
			book[i] = sc.nextInt();
		}
		
	    for(int i=1;i<=q;i++) {
	        len[i] = sc.nextInt();
	        num[i] = sc.nextInt();
	        // 10的 len[i]次方
	        int tmp = (int) Math.pow(10,len[i]),min=Integer.MAX_VALUE;
	        for(int j=1;j<=n;j++) {
	        	if(book[j]%tmp==num[i]&&book[j]<min){
	        		min=book[j];
	        	}   	
	        }
	        if(min!=Integer.MAX_VALUE){
	        	System.out.println(min);
	        }else{
	        	System.out.println(-1);
	        }
	    }    
		   
		sc.close();
	}
}