// C.cpp: определяет точку входа для консольного приложения.
//

//#include "stdafx.h"
#include <cmath>
#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

vector <ll> up, down;

bool comp(ll a, ll b)
{
	return(a > b);
}

int main()
{
	ll last, count, n, data;
	char ch;
	cin >> last >> count >> n;
	for (int i = 0; i < n; i++)
	{
		cin >> data >> ch;
		if (ch == 'U')
			up.push_back(data);
		else
			down.push_back(data);
		if (ch == 'U' && data == 0)
			up.pop_back(), down.push_back(0);
	}
	sort(up.begin(), up.end(), comp);
	sort(down.begin(), down.end());
	ll mn, ans = 0, ans1 = 0, mx = count + up.size();
	for (int i = 0; i <= 2 * (mx); i++)
	{
		if (ans1 == mx)
		{
			cout << ans << endl;
			break;
		}
		mn = min(last - up[0], down[0]);
		for (int j = 0; j < up.size(); j++)
			up[j] += mn;
		for (int j = 0; j < down.size(); j++)
			down[j] -= mn;
		if (up[0] == last)
			{
			up.erase(up.begin());
			down.push_back(last);
			ans1++;
		}
		if (down[0] == 0)
		{
			down.erase(down.begin());
			up.push_back(0);
		}
		sort(up.begin(), up.end(), comp);
		sort(down.begin(), down.end());
		ans += mn;
		//cout << mn << ' ' << up.size() << ' ' << down.size() << endl;
	}
	//system("pause");
	return 0;
}

/*
ё
4
1
2
4 U
0 U

*/