#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
//using mint = modint998244353;
const int dx[4]={0,1,0,-1};
const int dy[4]={1,0,-1,0};

ll f(ll a,ll b){
    ll c=1;
    vector<ll>ans;
    if(b%a==0)return 0;
    while(b-a*c>=c-1&&b-a*c>0){
        c++;
        ll d=(b-a*c)%(c-1);
        ll e=(b-a*c)/(c-1);
        if(d==0&&e>0)ans.push_back (e);
    }
    if(!ans.empty())return ans[ans.size()-1];
    return -1;
}

int main() {
    int t;
    cin>>t;
    while(t--){
        ll a,b;
        cin>>a>>b;
        cout<<f(a,b)<<endl;
    }
    return 0;
}