#include <vector>
#include <limits>
#include <iostream>
#include <cmath>

using namespace std;

int64_t n, ln;
vector<int64_t> times[2];

int64_t ans;

void solve_switch(int dir) {
    vector<int64_t> cur;
    for (int i = 0; i < 2; ++i) {
        cur.push_back(0);
    }

    int64_t curTime = 0;
    int64_t curAns = 0;
    while (cur[0] < times[0].size() || cur[1] < times[1].size()) {
        if (cur[dir] >= times[dir].size()) {
            dir = 1 - dir;
            continue;
        }

        int64_t next = max(curTime, times[dir][cur[dir]]);
        while (cur[dir] < times[dir].size() && times[dir][cur[dir]] <= next) {
            curAns += max(int64_t(0), next - times[dir][cur[dir]]);
            cur[dir]++;
        }
        curTime = next + ln;
        dir = 1 - dir; 
    }
    ans = min(ans, curAns);
}

void solve_extend(int dir) {
    vector<int64_t> cur;
    for (int i = 0; i < 2; ++i) {
        cur.push_back(0);
    }

    int64_t curTime = 0;
    int64_t curAns = 0;
    while (cur[0] < times[0].size() || cur[1] < times[1].size()) {
        if (cur[dir] >= times[dir].size()) {
            dir = 1 - dir;
            continue;
        }

        int64_t next = max(curTime, times[dir][cur[dir]]);
        while (cur[dir] < times[dir].size() && times[dir][cur[dir]] <= next) {
            curAns += max(int64_t(0), next - times[dir][cur[dir]]);
            cur[dir]++;
        }
        while (cur[dir] < times[dir].size() && times[dir][cur[dir]] <= next + ln) {
            next = times[dir][cur[dir]];
            cur[dir]++;
        }
        curTime = next + ln;
        dir = 1 - dir; 
    }
    ans = min(ans, curAns);
}

int main() {
    cin >> n >> ln;
    for (int i = 0; i < n; ++i) {
        char c;
        int64_t t;
        cin >> c >> t;
        if (c == 'N') {
            times[0].push_back(t);
        } else {
            times[1].push_back(t);
        }
    }

    ans = std::numeric_limits<int64_t>::max();

    for (int dir = 0; dir < 2; ++dir) {
        solve_switch(dir);
        solve_extend(dir);
    }

    cout << ans << endl;
    return 0;
}