#include <fstream>
#include <climits>
using namespace std;
ifstream in ("furnici.in");
ofstream out ("furnici.out");
int maxim=INT_MIN;
int len, n;
void ReadandSolve()
{
    char caux;
    int aux;
    in>>len>>n;
    while (n--)
    {
        in>>aux>>caux;
        if (caux=='D')
            aux=len-aux;
        if (aux>maxim)
        {
            maxim=aux;
        }
    }
}
void Print()
{
    out<<maxim;
}
int main()
{
    ReadandSolve();
    Print();
    return 0;
}