#include <bits/stdc++.h>
using namespace std;
int gcdsum(int x)
{
    int s=0;for(int i=1;i<=x;i++)if(x%i==0)s+=i;
    return s;
}
int main()
{
    int t;scanf("%d",&t);
    while(t--)
    {
        int x,y,ans=0;scanf("%d%d",&x,&y);
        for(int i=x;i<=y;i++)if(gcdsum(i)>i*2)ans=max(ans,gcdsum(i)-i*2);
        if(ans>0)printf("%d\n",ans);
        else printf("-1\n");
    }
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int gcdsum(int x)
{
    int s=0;for(int i=1;i<=x;i++)if(x%i==0)s+=i;
    return s;
}
int main()
{
    int t;scanf("%d",&t);
    while(t--)
    {
        int x,y,ans=0;scanf("%d%d",&x,&y);
        for(int i=x;i<=y;i++)if(gcdsum(i)>i*2)ans=max(ans,gcdsum(i)-i*2);
        if(ans>0)printf("%d\n",ans);
        else printf("-1\n");
    }
    return 0;
}