#include <bits/stdc++.h>   using namespace std;   void solve() {     int n;     cin >> n;     std::vector<int> v;     int maxi = 0;     for (long long i = 0; i < n; i++) {       int a;       cin >> a;       v.push_back(a);       maxi = max(maxi, a);     }     int ans = -1;     for (long long i = 0; i < n; i++) {       if (v[i] == maxi &&           ((v[i] > v[i + 1] && i < n - 1) || (i > 0 && v[i] > v[i - 1]))) {         ans = i + 1;       }     }     cout << ans <<   n ;   }   int main() {     ios::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     int t = 1;     cin >> t;     while (t--) {       solve();     }     return 0;   }   