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

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> ii;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<ii> vii;

#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define rep(i,a,b) for(auto i=(a); i<(b); ++i)
#define REP(i,n) rep(i,0,n)
#define all(v) (v).begin(), (v).end()
#define rs resize
#define DBG(x) cerr << __LINE__ << ": " << #x << " = " << (x) << endl

const ld PI = acos(-1.0);
template<class T> using min_queue =
priority_queue<T, vector<T>, greater<T>>;
template<class T> int sz(const T &x) {
    return (int) x.size(); // copy the ampersand(&)!
}

template<class T> ostream& operator<<(ostream &os, vector<T> &v) {
    os << "\n[";
    for(T &x : v) os << x << ',';
    return os << "]\n";
}

struct pairhash {
    public:
    template<typename T1, typename T2>
    size_t operator()(const pair<T1, T2> &p) const {
        size_t lhs = hash<T1>()(p.x);
        size_t rhs = hash<T2>()(p.y);
        return lhs ^ (rhs+0x9e3779b9+(lhs<<6)+(lhs>>2));
    }
};

const ll INF = 1'000'000'000'000'000;

void run() {
	ll n, l;
	cin >> n >> l;
	vii T(n);
	for (ll i = 0; i < n; i++) {
		string s;
		ll t;
		cin >> s >> t;
		ll d;
		if (s[0] == 'N') {
			d = 0;
		} else {
			d = 1;
		}
		T[i] = {t,d};
	}
	vvi A(2, vi(n+1, INF));
	A[0][0] = 0;
	A[1][0] = 0;

	vvi S(2, vi(n+1, 0)), C(2, vi(n+1, 0));
	for (ll i = 0; i < n; i++) {
		S[0][i+1] = S[0][i];
		C[0][i+1] = C[0][i];
		S[1][i+1] = S[1][i];
		C[1][i+1] = C[1][i];
		S[T[i].y][i+1] += T[i].x;
		C[T[i].y][i+1] += 1;
	}
	
	ll t = 0, i1 = 0, i2 = 0;
	deque<pair<ii, ii>> Q;
	while (i1 < n || Q.size() > 0) {
		bool train = (i1 < n && (Q.size() == 0 || T[i1].x <= Q[0].x.x));
		if (train) {
			t = T[i1].x;
		} else {
			t = Q[0].x.x;
		}
		while (i2 < n && T[i2].x < t + l) i2++;
		ll t2 = t+l;
		if (train) {
			ll d = T[i1].y;
			ll bc = INF;
			for (ll j = 0; j <= i1; j++) {
				ll c = A[d][j] + t2*(C[1-d][i2] - C[1-d][j]) - (S[1-d][i2] - S[1-d][j]);
				bc = min(bc, c);
			}
			i1++;
			Q.pb({{t2, 1-d}, {i1, bc}});
		} else {
			pair<ii, ii> q = Q[0];
			Q.pop_front();
			ll d = q.x.y;
			if (q.y.y < A[d][q.y.x]) {
				A[d][q.y.x] = q.y.y;
				ll c = q.y.y + t2*(C[1-d][i2] - C[1-d][q.y.x]) - (S[1-d][i2] - S[1-d][q.y.x]);
				Q.pb({{t2, 1-d}, {i1, c}});
			}
		}
	}
	cout << min(A[0][n], A[1][n]) << endl;
}

signed main() {
    // DON'T MIX "scanf" and "cin"!
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout << fixed << setprecision(20);
    run();
    return 0;
}