HDU 1563 Find your present!

#include <iostream>
#include <algorithm>
using namespace std ;
int main()
{
int n;
while(scanf("%d",&n),n)
{
int a[201];
a[1]=a[n+1]=-1;
for(int i=1;i<=n;i++)
scanf("%d",&a[i]);
sort(a+1,a+1+n);
for(int i=1;i<=n;i++)
if(a[i]!=a[i-1]&&a[i]!=a[i+1])
{
printf("%d\n",a[i]);
break;
}
}
return 0;
}