Lonely Integer

Consider an array of  integers, , where all but one of the integers occur in pairs. In other words, every element in  occurs exactly twice except for one unique element.

Given , find and print the unique element.

Input Format

The first line contains a single integer, , denoting the number of integers in the array. 
The second line contains  space-separated integers describing the respective values in .

Constraints

• It is guaranteed that  is an odd number.
• , where .

Output Format

Print the unique number that occurs only once in  on a new line.

Sample Input 0

1
1

Sample Output 0

1

Explanation 0 
The array only contains a single , so we print  as our answer.

Sample Input 1

3
1 1 2

Sample Output 1

2

Explanation 1 
We have two 's and one . We print , because that's the only unique element in the array.

Sample Input 2

5
0 0 1 2 1

Sample Output 2

2

Explanation 2 
We have two 's, two 's, and one . We print , because that's the only unique element in the array.

Solution:

#include<iostream>

using namespace std;

int main(){

int n;

cin>>n;

int a[1000]={0},b;

for(int i=0;i<n;i++){

    cin>>b;

    a[b]++;

}

for(int i=0;i<1000;i++){

if(a[i]==1)

    cout<<i;}

}