#include <stdio.h>
int main()
{
int t, ii = 0, m, n, num[20], max = 0, k;
scanf("%d", &t);
while (ii < t)
{
scanf("%d%d", &m, &n);
max = 0;
for (int i = n; i >= m; i--)
{
k = 0;
for (int j = 2; j < i; j++)
{
if (i % j == 0)
k++;
}
if (k >= max)
{
max = k;
num[ii] = i;
}
}
if (max == 0)
num[ii] = -1;
ii++;
}
for (int i = 0; i < t; i++)
{
printf("%d\n", num[i]);
}
}