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#include <bits/stdc++.h>

#define ll long long
#define ld long double
#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define FOR(i,l,r) for(int i=(l);i<=(r);i++)
#define ROF(i,r,l) for(int i=(r);i>=(l);i--)
using namespace std;
ll infl=1000000000000000007;
int inf=1000000007;

#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

const int N=200007;

ll a[N];

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int tt;
    cin>>tt;
    while(tt--)
    {
		int n;
		cin>>n;
		FOR(i,1,n) cin>>a[i];
		ll l=0,r=1000000000,sr,ans=-1;
		while(l<=r)
		{
			sr=(l+r)/2;
			bool ok=1;
			ll sum=0;
			FOR(i,1,n)
			{
				ll L=0,R=min(1000LL,sr-sum),SR,k=-1;
				while(L<=R)
				{
					SR=(L+R)/2;
					if(sum*SR*(sr-sum-SR)+SR*(SR-1)/2*(sr-SR)+SR*(SR-1)*(SR-2)/6>=a[i])
					{
						k=SR;
						R=SR-1;
					}
					else L=SR+1;
				}
				debug(i,k);
				if(k==-1||sum+k>sr)
				{
					ok=0;
					break;
				}
				sum+=k;
			}
			if(ok)
			{
				r=sr-1;
				ans=sr;
			}
			else l=sr+1;
		}
		cout<<ans<<endl;
	}
    
    
    return 0;
}