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;
}
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1704A - Two 0-1 Sequences | 1467A - Wizard of Orz |
1714E - Add Modulo 10 | 1714A - Everyone Loves to Sleep |
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1264F - Beautiful Fibonacci Problem | 52A - 123-sequence |
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215B - Olympic Medal | 1445A - Array Rearrangment |
1351A - A+B (Trial Problem) | 935B - Fafa and the Gates |
1291A - Even But Not Even | 1269A - Equation |