#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;
using ll = long long;


int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    ll q,y;
    cin>>q>>y;
    ll n = q;
    vector<ll> s(n);
    auto calc = [](string now){
        ll ans = 0;
        for(int i = 0;i<now.size();i++){
            ans *= 10;
            ans += now[i] - '0';
        }
        return ans;
    };
    for(int i = 0;i<n;i++){
        string now;
        cin>>now;
        if(now=="X") s[i] = -1;
        else if(now=="+") s[i] = -2;
        else if(now=="max") s[i] = -3;
        else if(now=="min") s[i] = -4;
        else s[i] = calc(now);
    }
    ll right = max(10ll,y + 10);
    ll left = -1;

    auto get = [&](ll now) {
        vector<ll> a;
        for(int i = 0;i<n;i++){
            if(s[i]==-1) a.push_back(now);
            else if(s[i]==-2){
                ll p = 0;
                p += a.back();
                a.pop_back();
                p += a.back();
                a.pop_back();
                if(p>y) return p;
                a.push_back(p);
            }else if(s[i]==-3){
                ll p = 0;
                p += a.back();
                a.pop_back();
                p = max(p,a.back());
                a.pop_back();
                if(p>y) return p;
                a.push_back(p);
            }else if(s[i]==-4){
                ll p = 0;
                p += a.back();
                a.pop_back();
                p = min(p,a.back());
                a.pop_back();
                if(p>y) return p;
                a.push_back(p);
            }else{
                a.push_back(s[i]);
            }
        }
        return a[0];
    };
    while(right-left>1){
        ll mid = (right+left) / 2;
        if(get(mid)>=y) right = mid;
        else left = mid;
    }
    if(get(right)==y) cout<<right<<endl;
    else cout<<-1<<endl;
}