#include <bits/stdc++.h>

using namespace std;
int main() {
	int t; cin >> t;
		while (t--) {
			int n; cin >> n;
			vector<int> v(n);
			int m = 0 , co=0 ;
			for (int i = 0; i < n; i++)
			{
				cin >> v[i];
				m = max(v[i], m);
			}
			for (int i = 0; i < n; i++)
			{
				if (v[i] == m)
					co++;
			}
			if (co > 2)
				cout << -1 << endl;
			else
			{
			    if(co ==2)
				cout << n - 1 << endl;
				else
				cout << n  << endl;

			}
			v.clear();
		}
}