#include <bits/stdc++.h>
template <class T>
void chkmin(T &x, const T &y) {
  if (x > y) x = y;
}
using ll = long long;

int main() {
  std::cin.tie(0)->sync_with_stdio(0);
  int n;
  ll z, ans = 0;
  std::array<std::vector<ll>, 2> a;
  std::cin >> n >> z;
  for (int i = 0; i < n; i++) {
    char c;
    ll t;
    std::cin >> c >> t;
    a[c == 'B'].push_back(t);
    ans += t;
  }
  for (auto &v : a) std::sort(v.begin(), v.end());
  n = a[0].size();
  int m = a[1].size();
  std::array<std::vector<std::vector<ll>>, 2> dp, g;
  dp.fill(std::vector(n + 1, std::vector(m + 1, (ll)1e18))), g = dp;
  dp[0][n][m] = dp[1][n][m] = 0;
  for (int i = n - 1; i >= 0; i--) {
    dp[0][i][m] = dp[0][i + 1][m] + a[0][i];
  }
  for (int i = m - 1; i >= 0; i--) {
    dp[1][n][i] = dp[1][n][i + 1] + a[1][i];
  }
  for (int i = n - 1; i >= 0; i--) {
    for (int j = m - 1; j >= 0; j--) {
      for (int t : {0, 1}) {
        chkmin(dp[t][i][j], dp[t][i + !t][j + t]);
        std::array p{i, j};
        if (a[t][p[t]] + z >= a[t ^ 1][p[t ^ 1]]) {
          if (g[t][i + t][j + !t] != 1e18) {
            g[t][i][j] = g[t][i + t][j + !t] + a[t][p[t]] + z;
          } else {
            ll lim = a[t][p[t]] + z, sum = 0;
            p[t]++;
            for (int c = t ^ 1;; c ^= 1) {
              bool ok = 0;
              while (p[c] < (int)a[c].size() && a[c][p[c]] < lim)
                p[c]++, ok = 1, sum += lim;
              chkmin(g[t][i][j], dp[c][p[0]][p[1]] + sum);
              if (!ok) break;
              lim += z;
            }
          }
          chkmin(dp[t][i][j], g[t][i][j]);
        } else {
          chkmin(dp[t][i][j], dp[t ^ 1][i + !t][j + t]);
        }
        dp[t][i][j] += a[t][t ? j : i];
      }
    }
  }
  std::cout << std::min(dp[0][0][0], dp[1][0][0]) - ans << '\n';
}