#include<bits/stdc++.h>
#define faster ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
int lcd(int x,int y)
{
    int mn=min(x,y);
    for (int i=2;i<=mn;i++)
    {
        if (x%i==0 && y%i==0)
        {
            return i;
        }
    }

    return -1;
}

int main()
{
    faster
    //int t=1;
    int t; cin >> t;
    while (t--)
    {
        int x,y; cin >> x >> y;
        cout << lcd(x,y) << endl;
    }

}