#include <stdexcept> // for access to logic_error
#include <iostream>
#include <stack>

// define classes Expr, Operand, Operator, Plus and Mult here!
// file separation is not required.

Expr* top_and_pop(stack<Expr*>& s)
{
  if ( s.empty() )
    throw logic_error{"Too few operands"};
  
  Expr* e{ s.top() };
  s.pop();
  return e;
}

int main()
{
  stack<Expr*> exprs;
  string input;
  while ( cin >> input )
  {
    switch( input.at(0) )
    {
      case '+':
      {
        Expr* right{ top_and_pop( exprs ) };
        Expr* left{ top_and_pop( exprs ) };
        exprs.push( new Plus{left, right} );
      }
      break;
      
      case '*':
      {
        Expr* right{ top_and_pop( exprs ) };
        Expr* left{ top_and_pop( exprs ) };
        exprs.push( new Mult{left, right} );
      }
      break;
        
      default:
      {
        exprs.push( new Operand{ stod(input) } );
      }
      break;        
    }
  }

  Expr* e{ exprs.top() };
  e->print( cout );
  cout << endl << "Answer: " << e->evaluate() << endl;

  while ( ! exprs.empty() )
  {
    delete top_and_pop( exprs );
  }
  
  return 0;
}