Untitled

class Solution {
public:
    long long dividePlayers(vector<int>& skill) {
        sort(skill.begin(),skill.end());
        int n = skill.size();
        int sum = skill[0] + skill[n-1];
        long long ans = skill[0] * skill[n-1];
        int b = 1 , e = n-2;
        
        while(b<=e) {
            long long  newSum = skill[b] + skill[e];
            
            if(newSum != sum)return -1;
            
            ans+=skill[b] * skill[e];
            b++, e--;
        }
        
        return ans;
    }
};