Help me in solving XOREQN problem

help
,
1

My issue

I have tried editorial’s approach to this problem but i don’t why can’t i pass all testcase.
Please help me

My code

#include <bits/stdc++.h>
using namespace std;

#define int long long


void solve(){
    int n;
    cin>>n;
    vector<int>v(n);
    for(int &i:v)
        cin>>i;
    
    int x=0;
    for(int i=0;i<=60;i++){
        int cnt=0;
        for(int ele:v){
            ele= ele+x;
            if((ele & (1<<i) )!=0){
                cnt^=1;
            }
        }
        if (cnt==1){
            x=x | (1ll<<i);
        }
    }
    
    int verify=0;
    for(int i:v){
        verify^= (i+x);
    }
    if(verify){
        cout<<-1<<endl;
        return;
    }
    cout<<x<<endl;
}



signed main() {
	// your code goes here
	int t;
	cin>>t;
	while(t--){
	    solve();
	}
	return 0;
}

Problem Link: Xor Equation Practice Coding Problem - CodeChef