#include<bits/stdc++.h>
using namespace std;

int main()
{
    int N, tams[10005] = {0}, iguais;
    char pes[10005];

    cin >> N;

    for (int i = 0; i < N; ++i)
    {
        cin >> tams[i] >> pes[i];
        for (int j = 0; j < i; ++j)
        {
            if (tams[j] == tams[i] && (pes[i] == 'E' && pes[j] == 'D' || pes[i] == 'D' && pes[j] == 'E'))
            {
                    iguais++;
                    tams[i] = 323232 + iguais;
                    tams[j] = 4747 + iguais;
            }
        }
    }

    cout << iguais;

    return 0;
}