85D - Sum of Medians - CodeForces Solution

#include <bits/stdc++.h>
#define pos lower_bound(v.begin(),v.end(),x)
using namespace std;
int n,x;
vector<int> v;
int main() {
cin>>n;
while(n--){
string s;
cin>>s;
if(s[0]=='s'){
long long r=0;
for(int i=2;i<v.size();i+=5)r+=v[i];
cout<<r<<endl;
}
else{
cin>>x;
if(s[0]=='a')v.insert(pos,x);
else v.erase(pos);
}
}
return 0;
}