for i in range(int(input())):
a = input()
lst = list(map(int, input().split()))
sl = {}
for el in lst:
sl[el] = 1 + (sl[el] if el in sl else 0)
if sl[el] > 2:
print(el)
break
else:
print(-1)#include<bits/stdc++.h>
using namespace std;
int main()
{
int c;
cin>>c;
for(int t=0; t<c; t++)
{
int n,out=0;
cin>>n;
int a[n+5],b[n+5]= {0};
for(int i=0; i<n; i++)
{
cin>>a[i];
b[a[i]]+=1;
}
for(int j=0; j<=n; j++)
{
if(b[j]>=3)
{
out=j;
}
}
if(out==0)
cout<<"-1"<<endl;
else
cout<<out<<endl;
}
return 0;
}
22E - Scheme | 1566A - Median Maximization |
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1208B - Uniqueness | 1384A - Common Prefixes |
371A - K-Periodic Array | 1542A - Odd Set |
1567B - MEXor Mixup | 669A - Little Artem and Presents |
691B - s-palindrome | 851A - Arpa and a research in Mexican wave |
811A - Vladik and Courtesy | 1006B - Polycarp's Practice |
1422A - Fence | 21D - Traveling Graph |
1559B - Mocha and Red and Blue | 1579C - Ticks |
268B - Buttons | 898A - Rounding |
1372B - Omkar and Last Class of Math | 1025D - Recovering BST |
439A - Devu the Singer and Churu the Joker | 1323A - Even Subset Sum Problem |