Bestcoder Round8

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int main()
{
    int n;
    while (cin >> n)
    {
        vector<long long> vec,temp;
        long long a;
        //读取数据
        while (n--){
            cin >> a;
            temp.push_back(a);
        }
        //计算加法，压入vec中    
        int i, j;
        for (i = 0; i < (int)temp.size() - 1;i++)
        for (j = i + 1; j < (int)temp.size(); j++)
            vec.push_back(temp[i] + temp[j]);
        //排序，去重
        sort(vec.begin(), vec.end());
        vector<long long>::iterator ite_end;
        ite_end = unique(vec.begin(), vec.end());
        vec.erase(ite_end, vec.end());
        //遍历求和
        long long sum=0;
        vector<long long>::iterator ite;
        for (ite = vec.begin(); ite != vec.end(); ite++)
            sum += *ite;
        cout << sum << endl;
    }
    return 0;
}