Problem Description

In the new year party, everybody will get a “special present”.Now it’s your turn to get your special present, a lot of presents now putting on the desk, and only one of them will be yours.Each present has a card number on it, and your present’s card number will be the one that different from all the others.For example, there are 5 present, and their card numbers are 1, 2, 3, 2, 1.so your present will be the one with the card number of 3, because 3 is the number that different from all the others.

Input

The input file will consist of several cases.
Each case will be presented by an integer n (1<=n<=200, and n is odd) at first. Following that, n positive integers will be given in a line. These numbers indicate the card numbers of the presents.n = 0 ends the input.

Output

For each case, output an integer in a line, which is the card number of your present.

Sample Input

5
1 1 3 2 2
3
1 2 1
0

My code:

```#include
#include
using namespace std;
int main(void)
{
#ifndef ONLINE_JUDGE
freopen("in.txt", "r", stdin);
#endif
int n, f;
while (cin>>n)
{
if (n == 0)break;
for (int i = 1; i <= n; i++)
cin >> f[i];
sort(f+1, f + n+1);
f = 0;
for (int i = 0; i < n-1; i++)
{
if (f[i] != f[i + 1] && f[i + 1] != f[i + 2])
cout << f[i + 1] << endl;
}
if (f[n - 1] != f[n])
cout << f[n] << endl;

}
return 0;
}

```