An array of length n, with address from 1 to n inclusive, contains entries from the set {1,2,...,n-1} and there's exactly two elements with the same value. Your task is to find out the value.
Input
Input contains several cases.
Each case includes a number n (1<n<=10^6), which is followed by n integers.
The input is ended up with the end of file.
Output
Your must output the value for each case, one per line.
Sample Input
2
1 1
4
1 2 3 2
Sample Output
1
2
#include <iostream>
#include<cstdio>
using namespace std;
int main(int argc, char** argv)
{
int n;
while(scanf("%d",&n)!=EOF){
if(n!=-1){
int *p=new int[n];
int t,m;
while(n--){
cin>>t;
if(p[t]==0)
p[t]=1;
else
m=t;
}
cout<<m<<endl;
delete p;
}
else
break;
}
return 0;
}
