#include<bits/stdc++.h>
#define poly vector<int>
#define IOS ios::sync_with_stdio(false)
#define ll long long
#define mp make_pair
#define mt make_tuple
#define pa pair < int,int >
#define fi first
#define se second
#define inf 1e18
#define mod 998244353
#define sz(x) ((int)((x).size()))
#define int ll
#define N 200005
using namespace std;
int n,a[N];
void BellaKira()
{
    cin>>n;
    int sm=0,bl=1;
    for (int i=0;i<n;i++)
        cin>>a[i],sm+=a[i],bl&=(a[i]==0);
    if (sm<0||!bl&&sm==0)
    {
        cout<<"-1\n";
        return;
    }
    if (bl)
    {
        cout<<0<<'\n';
        return;
    }
    int ans=0;
    multiset<pa>s;
    for (int i=0;i<n;i++) s.insert(mp(a[i],i));
    while (1)
    {
        int i=(*s.begin()).se;
        if (a[i]>=0)
        {
            cout<<ans<<'\n';
            return;
        }
        s.erase(s.begin());
        ans++;
        s.erase(s.find(mp(a[(i+n-1)%n],(i+n-1)%n)));
        s.erase(s.find(mp(a[(i+1)%n],(i+1)%n)));
        a[(i+n-1)%n]+=a[i];
        a[(i+1)%n]+=a[i];
        s.insert(mp(a[(i+n-1)%n],(i+n-1)%n));
        s.insert(mp(a[(i+1)%n],(i+1)%n));
        a[i]=-a[i];
        s.insert(mp(a[i],i));
    }
    cout<<ans<<'\n';
}
signed main()
{
    IOS;
    cin.tie(0);
    int T=1;
    cin>>T;
    while (T--)
    {
        BellaKira();
    }
}