#include <array>
#include <functional>
#include <iostream>
#include <vector>
using namespace std;

int main() {
	int n;
	long long L;
	cin >> n >> L;
	vector<long long> a, b;
	a.push_back(-1);
	b.push_back(-1);
	for(int i = 0; i < n; ++i) {
		char c;
		long long t;
		cin >> c >> t;
		(c == 'N' ? a : b).push_back(t);
	}
	auto A = a.size(), B = b.size();
	auto INF = 1LL << 60;
	array<vector<vector<long long>>, 2> dp;
	for(auto& v : dp) {
		v.resize(A + 1);
		for(auto& w : v) {
			w.resize(B + 1, INF);
		}
	}
	dp[0][1][0] = 0;
	dp[1][0][1] = 0;

	int chains = 0;
	int whiles = 0;

	// Forward DP when:
	// - last train from side k
	// - i trains from left done
	// - j trains from right done
	// - current time t
	// - for total cost
	std::function<void(int, int, int, long long, long long)> chain;
	chain = [&](int k, int i, int j, long long t, long long cost) {
		chains += 1;
		if(k == 0) {
			while(i + 1 < A && a[i + 1] <= t) {
				whiles += 1;
				cost += t - a[i];
				i += 1;
			}
			if(a[i] > t) {
				dp[k][i][j] = min(dp[k][i][j], cost);
				return;
			}
			cost += t - a[i];
			dp[k][i + 1][j] = min(dp[k][i + 1][j], cost);
			if(j + 1 < B) {
				chain(1 - k, i, j + 1, t + L, cost);
			}
		} else {
			while(j + 1 < B && b[j + 1] <= t) {
				whiles += 1;
				cost += t - b[j];
				j += 1;
			}
			if(b[j] > t) {
				dp[k][i][j] = min(dp[k][i][j], cost);
				return;
			}
			cost += t - b[j];
			dp[k][i][j + 1] = min(dp[k][i][j + 1], cost);
			if(i + 1 < A) {
				chain(1 - k, i + 1, j, t + L, cost);
			}
		}
	};

	for(int i = 0; i < A; ++i) {
		for(int j = 0; j < B; ++j) {
			if(i > 0 && dp[0][i][j] < INF) {
				chain(0, i, j, a[i], dp[0][i][j]);
			}
			if(j > 0 && dp[1][i][j] < INF) {
				chain(1, i, j, b[j], dp[1][i][j]);
			}
		}
	}
	cout << min(dp[0][A][B - 1], dp[1][A - 1][B]) << endl;
	cerr << "chains: " << chains / 100000 << endl;
	cerr << "whiles: " << whiles / 100000 << endl;
}