#include <iostream>
#include <cstdlib>
using namespace std;
int stos[11];
int nr_stosu;
char znak;
void push()
{
cin>>stos[nr_stosu];
if(nr_stosu>=10)
{
cout<<":("<<endl;
}
else
{
cout<<":)"<<endl;
nr_stosu=nr_stosu+1;
}
}
void pop()
{
if(nr_stosu>=1)
{
nr_stosu=nr_stosu-1;
cout<<stos[nr_stosu]<<endl;
}
else
{
cout<<":("<<endl;
exit(0);
}
}
int main()
{
while ((znak!='+')||(znak!='-'))
{
cin>>znak;
if(znak=='+')
{
push();
}
else if(znak=='-')
{
pop();
}
}
return 0;
}
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