#include <iostream>
#include <fstream>
using namespace std;
ifstream f("numere.in");
ofstream g("numere.out");
int n,m,v[1000];
class prob3
{
private :
    int BinSearch(int x);
public:
    void rez3();
};
int prob3::BinSearch(int x)
{
    int st=1,dr=n,mij;
    while(st<=dr)
    {
        mij=(st+dr)/2;
        if(v[mij]==x)return mij;
        else if(v[mij]>x)dr=mij-1;
        else st=mij+1;
    }
    return 0;
}
void prob3::rez3()
{
    f>>n>>m;
    for(int i=1; i<=n; i++)f>>v[i];
    int k,x;
    for(int i=1; i<=m; i++)
    {
        f>>k>>x;
        if(BinSearch(x))g<<k*BinSearch(x)<<'\n';
        else g<<"-1\n";;
    }
    g.close();
}
int main()
{
    prob3 ob;
    ob.rez3();
    return 0;
}