#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define all(x) (x).begin(), (x).end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rrep(i, n) for(int i = (int)(n - 1); i >= 0; i--)
template <typename T> bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template <typename T> bool chmin(T &a,const T &b){if(a>b){a=b;return true;}return false;}
using ll = long long;
#define int ll
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vb = vector<bool>;
using vvb = vector<vector<bool>>;
using vs = vector<string>;
using pii = pair<int, int>;
// using mint = modint!!!number!!!;

signed main(){
  int q, y; cin >> q >> y;
  vs s(q); rep(i, q) cin >> s.at(i);
  __int128_t ok = 1ll << 60, ng = -1;
  while(ok - ng > 1){
  	__int128_t mid = (ok + ng) / 2;
  	vector<__int128_t> a; int n = 0;
  	rep(i, q){
  		if(s.at(i) == "X"){
  			a.push_back(mid);
  			n++;
  		}
  		else if(s.at(i) == "+"){
  			a.at(n - 2) += a.at(n - 1);
  			a.erase(a.begin() + n - 1);
  			n--;
  		}
  		else if(s.at(i) == "min"){
  			chmin(a.at(n - 2), a.at(n - 1));
  			a.erase(a.begin() + n - 1);
  			n--;
  		}
  		else if(s.at(i) == "max"){
  			chmax(a.at(n - 2), a.at(n - 1));
  			a.erase(a.begin() + n - 1);
  			n--;
  		}
  		else{
  			a.push_back(stoll(s.at(i)));
  			n++;
  		}
  	}
  	(a.at(0) >= y ? ok : ng) = mid;
  }
  __int128_t mid = ok, n = 0; vector<__int128_t> a;
  rep(i, q){
  		if(s.at(i) == "X"){
  			a.push_back(mid);
  			n++;
  		}
  		else if(s.at(i) == "+"){
  			a.at(n - 2) += a.at(n - 1);
  			a.erase(a.begin() + n - 1);
  			n--;
  		}
  		else if(s.at(i) == "min"){
  			chmin(a.at(n - 2), a.at(n - 1));
  			a.erase(a.begin() + n - 1);
  			n--;
  		}
  		else if(s.at(i) == "max"){
  			chmax(a.at(n - 2), a.at(n - 1));
  			a.erase(a.begin() + n - 1);
  			n--;
  		}
  		else{
  			a.push_back(stoll(s.at(i)));
  			n++;
  		}
  	}
  	cout << (a.at(0) == y ? int(ok) : -1) << endl;
}