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

using std::cin;
using std::cout;
using std::vector;
using std::string;

void WORRY(vector<bool>& vv, int index) {
    vv[index] = false;
}
void QUIET(vector<bool>& vv, int index) {
    vv[index] = true;
}
void COME(vector<bool>& vv, int value) {
    vv.resize(vv.size() + value, true);
}
int WORRY_COUNT(vector<bool>& vv) {
    int result = std::count(begin(vv), end(vv), false);
    return result < 0 ? 0 : result;
}

int main() {
    vector<bool> queue = {};
    int n = 0;
    cin >> n;
    int temp = 0;
    string opcode = "";
    for (size_t i(0); i < n; i++) {
        cin >> opcode;
        if (opcode == "COME") {
            cin >> temp;
            COME(queue, temp);
        }
        else if (opcode == "QUET") {
            cin >> temp;
            QUIET(queue, temp);
        }
        else if (opcode == "WORRY") {
            cin >> temp;
            WORRY(queue, temp);
        }
        else if (opcode == "WORRY_COUNT") {
            cout << WORRY_COUNT(queue) << std::endl;
        }
    }

    return 0;
}