#include <iostream>
#include <iomanip>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <string>
#include <vector>
using namespace std;
class Hotel
{
    int m;
    int c = -1;
    bool occupied[16];
public:
    Hotel(){
        for(int i = 0; i < 16; i++)
            occupied[i] = false;
    };
    bool is_occupied(int p)
    {
        if(occupied[p-1] == true)
            return false;
        else
            return true;
    }
    void free_room(int p)
    {
        occupied[p] = false;
    }
    int count_free()
    {
        int count = 0;
        for(int i = 0; i < 16; i++){
            if(occupied[i] == false) count++;
        }
        return count;
    }
    int find_room()
    {
        for(int i = 0; i < 16; i++)
        {
            if(occupied[i]==false){
                occupied[i]=true;
                return i;
            }
        }
        return c;
    }
};
int main() {
    int n, l;
    string str;
    cin >> n;
    Hotel a;
    for(int i = 0; i < n; i++){
        cin >> str;
        if(str=="RESERVE") cout << a.find_room() << endl;
        else if(str=="FREE"){
            cin >> l;
            a.free_room(l);
        }
        else if(str=="STATUS") cout << a.count_free() << endl;
    }
    return 0;
}