#include<iostream>
#include<vector>
#include <map>
using namespace std;

int n = 1000001;

int main(){
 
  int Test;
  cin>>Test;

  while(Test>0){
      int numberOfStudents;
    cin>>numberOfStudents;
    int max=-1;
    map <int,int> ans;
    for(int i=0;i<numberOfStudents;i++){
       int loki;
      cin>>loki;
      if(max < loki){
          max = loki;
        }
          ans[loki]+=1;
    }

      if (ans[max]==1){
          cout<<numberOfStudents<<endl;
      } else if(ans[max]==2){
          cout<<numberOfStudents-1<<endl;

      }
      else{
          cout<<-1<<endl;
      }
    
    Test--;
  }

}