#include<bits/stdc++.h>
using namespace std;
using ll=long long;
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}

void Solve(){
    ll N;
    cin>>N;
    if(N==0){
        cout<<0<<"\n";
        return;
    }
    int B=-1;
    for(int i=60;i>=0;i--){
        if(N>>i&1){
            B=i;
            break;
        }
    }
    assert(B!=-1);
    ll L=0,R=0;
    for(int i=0;i<=B/2;i++){
        R^=1LL<<i;
    }
    for(int i=B/2+1;i<=B;i++){
        if(N>>i&1){
            L^=1LL<<i;
            R^=1LL<<i;
        }
    }
    auto find_sq=[](ll x)-> ll {
        ll l=0,r=(ll)sqrt(x)+10;
        while(r-l>1){
            ll mid=(l+r)/2;
            if(mid*mid<=x)l=mid;
            else r=mid;
        }
        return l;
    };
    ll sl=find_sq(L),sr=find_sq(R);
    for(ll m=sl;m<=sr+1;m++){
        if(m*m<=(N^m)&&(N^m)<(m+1)*(m+1)){
            cout<<(N^m)<<"\n";
            return;
        }
    }
    cout<<-1<<"\n";
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T;
    cin>>T;
    while(T--){
        Solve();
    }
}