#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

using mint = modint998244353;

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

ll solve(ll Q, vector<string> &s, ll X) {
    ll last_val = 0;
    vector<ll> vec(0);
    ll len = vec.size();
    for (ll i = 0; i < Q; i++) {
        if (s[i] == "+" || s[i] == "min" || s[i] == "max") {
            ll val1 = vec[len - 1];
            ll val2 = vec[len - 2];
            vec.pop_back();
            vec.pop_back();
            if (s[i] == "+") {
                vec.push_back(val1 + val2);
            } else if (s[i] == "min") {
                vec.push_back(min(val1, val2));
            } else {
                vec.push_back(max(val1, val2));
            }
            len--;
        } else if (s[i] == "X") {
            vec.push_back(X);
            len++;
        } else {
            vec.push_back(stoll(s[i]));
            len++;
        }
    }
    // debug(vec);
    last_val = vec[0];
    return last_val;
}

int main() {
    ll Q, Y;
    cin >> Q >> Y;
    vector<string> s(Q);
    for (ll i = 0; i < Q; i++) {
        cin >> s[i];
    }

    ll ng = -1;
    ll ok = 10000000023;
    while (ok - ng > 1) {
        ll mid = (ok + ng) / 2;
        ll solved = solve(Q, s, mid);
        if (solved < Y) {
            ng = mid;
        } else {
            ok = mid;
        }
        // debug_out(mid, solved);
    }
    if (solve(Q, s, ok) != Y) {
        cout << -1 << endl;
    } else {
        cout << ok << endl;
    }
}