#include <bits/stdc++.h>

#define int long long

int time_per_meter = 1;

using namespace std;

vector<int> times_actions;
vector<int> distance_actions;

void check_actions(int distance, int time)
{
    for (int i = 0; i < distance_actions.size(); i++)
        if (distance_actions[i] == distance)
            time_per_meter++;

    for (int i = 0; i < times_actions.size(); i++)
        if (times_actions[i] == time)
            time_per_meter++;
}


signed main()
{
    vector<int> times(1001, -1);

    int n;
    cin >> n;

    for (int i = 0; i < n; i++)
    {
        pair<string, int> p;
        cin >> p.first >> p.second;

        if (p.second >= 0 && p.second <= 1000)
        {
            if (p.first == "T")
                times_actions.push_back(p.second);
            else
                distance_actions.push_back(p.second);
        }
    }

    times[0] = 0;
    check_actions(0, 0);

    for (int i = 1; i <= 1000; i++)
    {
        times[i] = times[i - 1] + time_per_meter;
        check_actions(i, times[i]);
    }

    cout << times[1000];

    return 0;
}