#include<iostream>
#include<vector>
#include<string>
using namespace std;
int main()
{
vector <int> stos;
string komenda;
while (komenda != "END")
{
cin >> komenda;
if (komenda == "PUSH")
{
int liczba;
cin >> liczba;
stos.push_back(liczba);
if (stos.size() == 100)
{
cout << "error" << endl;
return 0;
}
}
else if (komenda == "POP")
{
if (stos.empty() == true)
{
cout << "error" << endl;
return 0;
}
else
stos.pop_back();
}
}
for (int i = (stos.size())-1; i>=0; i--)
cout << stos[i] << endl;
}
{"html5":"htmlmixed","css":"css","javascript":"javascript","php":"php","python":"python","ruby":"ruby","lua":"text\/x-lua","bash":"text\/x-sh","go":"go","c":"text\/x-csrc","cpp":"text\/x-c++src","diff":"diff","latex":"stex","sql":"sql","xml":"xml","apl":"apl","asterisk":"asterisk","c_loadrunner":"text\/x-csrc","c_mac":"text\/x-csrc","coffeescript":"text\/x-coffeescript","csharp":"text\/x-csharp","d":"d","ecmascript":"javascript","erlang":"erlang","groovy":"text\/x-groovy","haskell":"text\/x-haskell","haxe":"text\/x-haxe","html4strict":"htmlmixed","java":"text\/x-java","java5":"text\/x-java","jquery":"javascript","mirc":"mirc","mysql":"sql","ocaml":"text\/x-ocaml","pascal":"text\/x-pascal","perl":"perl","perl6":"perl","plsql":"sql","properties":"text\/x-properties","q":"text\/x-q","scala":"scala","scheme":"text\/x-scheme","tcl":"text\/x-tcl","vb":"text\/x-vb","verilog":"text\/x-verilog","yaml":"text\/x-yaml","z80":"text\/x-z80"}