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

signed main() {
    int n, h;
    char t;
    int x;
    int cur = 0;
    int mx = 0;
    int mn = 0;

    cin >> n >> h;
    for (int i = 0; i < n; ++i) {
        cin >> t >> x;
        if (t == 'u') {
            cur += x;
            mx = max(mx, cur);
        }
        else {
            cur -= x;
            mn = min(mn, cur);
        }
    }
    if (mx - mn + 1 > h) {
        cout << 0;
    }
    else {
        cout << h - mx + mn;
    }
}