http://ac.jobdu.com/problem.php?pid=1174
#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
int a[1005];
int main()
{
int n,i,k;
while (scanf("%d",&n)!=EOF)
{
for (i=0;i<n;i++)
{
scanf("%d",&a[i]);
}
scanf("%d",&k);
int t=1;
sort(a,a+n);
for (i=1;i<n;i++)
{
if (a[i]!=a[i-1])
{
t++;
}
if (t==k)
{
printf("%d\n",a[i]);
break;
}
}
}
return 0;
}