func_code_string: /*    Solution by:-     --------------Sannidhay Vashal    ----------------NIT SRINAGAR       */   #include<iostream>   #include<vector>   #include<algorithm>   #include<stack>   #include<queue>   #include<map>   #include<math.h>   #include<climits>   #include<set>   #include<cstring>   #include<unordered_map>   #include <cstdlib>    #include<cmath>       #define fio ios_base::sync_with_stdio(false);cin.tie(NULL)   #define ll            long long int   #define ull           unsigned long long int   #define cinll(x)      ll x;cin>>x;   #define cini(x)       int x;cin>>x;   #define cins(x)       string x;cin>>x;   #define vect(x)       vector<ll> x;   #define vect1(x)      vector<ll> x;x.push_back(0);   #define pb(x)         push_back(x)   #define mp(x,y)       make_pair(x,y)   #define MAX           1e18   #define MIN           -1000000007   #define MOD           1000000007      using namespace std;      bool compare(pair<ll,ll> a,pair<ll,ll> b){     return a.second<b.second;   }      int main(){     cinll(t);     while(t--){       cinll(n);       vector<ll> arr;       unordered_map<ll,ll> mapit;       vector<pair<ll,ll>> ans;       for(ll i=0;i<n;i++) {         cinll(x);         arr.pb(x);         mapit[x]++;       }       ll anss = -1;       for(ll i=0;i<n;i++){         if(mapit[arr[i]]==1) ans.pb(mp(i+1,arr[i]));       }       sort(ans.begin(),ans.end(),compare);       if(ans.size()>=1) anss = ans[0].first;       cout<<anss<<  n ;     }     return 0;   }   