#include <vector>
#include <string>
#include <iostream>

using namespace std;


int main()
{
    int n, digit;
    vector < int > a;
    vector < string > v;
    cin >> n;
    string s;
    for (int i = 0; i < n; i++)
    {
        cin >> s;
        v.push_back(s);
    }
    for (int i = 0; i < n; i++)
    {
        if (v[i][0] == '-')
        {
            cout << a[int(a.size() - 1)] << endl;
            a.erase(a.end() - 1);
        }
        else
        {
            int  ten = 1;
            digit = 0;
            int j = int(v[i].length()) - 1;
            while (j >= 1)
            {
                digit += (int(v[i][j] - '0') * ten);
                ten *= 10;
                j--;
            }
            if (v[i][0] == '+')
                a.push_back(digit);
            else
                if (v[i][0] == '?')
                {
                    long long sum = 0;
                    for (int j = int(a.size()) - digit; j < int(a.size()); j++)
                        sum += a[j];
                    cout << sum << endl;
                }
        }
    }
}