////////////////////////////////////////////////////////
//
//  High School Programming Contest 2000
//
//  Implementation of level 0 of the takehome problem.
//
//  Author: Chad Barb [ hspc@cs.utah.edu ]
//
////////////////////////////////////////////////////////

// You may replace these with iostream and string.
#include <iostream.h>   // For cin and cout classes
#include <string.h>     // For strcmp() function
#include <stdlib.h>     // For exit()
                        
// Define a "Token" type that may have of one of the listed values.
enum Token
{
  TOKEN_ZERO,
  TOKEN_ONE,
  TOKEN_TWO,
  TOKEN_THREE,
  TOKEN_FOUR,
  TOKEN_FIVE,
  TOKEN_SIX,
  TOKEN_SEVEN,
  TOKEN_EIGHT,
  TOKEN_NINE,

  TOKEN_PLUS,
  TOKEN_MINUS,

  TOKEN_UNKNOWN

  // add your own tokens here.
};

// function prototypes
Token getSymbol();
int getNumber();
int lineValue();


//////////////////////////////////////////
//
//    the main function of the program.
//
//////////////////////////////////////////

int main()
{
  // infinite loop.
  // getToken() will exit() when it receives a "bye" token.
  while ( true )
  {
    // input and evaluate a line, then output it
    cout << lineValue() << endl;
  }

  return 0;
}

/////////////////////////////////////////////////////////////////////
//
//  Called repeatedly by main() to input and evaluate a single line.
//  Returns the result of the operation on that line.
//
/////////////////////////////////////////////////////////////////////

int lineValue()
{
  int operand1, operand2;  // the operands of the operation
  Token operation;	   // the operation type

  // get the operation specifics
  operand1  = getNumber();
  operation = getSymbol();
  operand2  = getNumber();

  // Ignore anything which remains on this line, so erroneous input doesn't 
  // mess up anything further (up to 1024 characters).
  // This is not required, since the program will not receive erroneous input
  // in normal use, but it may facilitate human testing somewhat.
  cin.ignore( 1024, '\n' );

  // do it, based on the operation
  switch( operation )
  {
    case TOKEN_PLUS:  return ( operand1 + operand2 );
    case TOKEN_MINUS: return ( operand1 - operand2 );
    default:          return 0;
  }
}

//////////////////////////////////////////////////////////////////////////
//
//  Called to get a number from cin (stdin).  This can call getToken()
//  repeatedly to accomplish its task.  In the simple case, it calls it
//  once, but once you implement multi-word numbers (like "one hundred"),
//  you will need some way of deciding when numbers end.
//
//////////////////////////////////////////////////////////////////////////

int getNumber()
{
  int inToken;

  // get the next symbol
  inToken = getSymbol();

  // decide what should be returned based on the received token.
  switch( inToken )
  {
    case TOKEN_ZERO:  return 0;
                      break;
    case TOKEN_ONE:   return 1;
                      break;
    case TOKEN_TWO:   return 2;
                      break;
    case TOKEN_THREE: return 3;
                      break;
    case TOKEN_FOUR:  return 4;
                      break;
    case TOKEN_FIVE:  return 5;
                      break;
    case TOKEN_SIX:   return 6;
                      break;
    case TOKEN_SEVEN: return 7;
                      break;
    case TOKEN_EIGHT: return 8;
                      break;
    case TOKEN_NINE:  return 9;
                      break;
    default:          return 0;
  }
}

/////////////////////////////////////////////////
//
//  Gets a single symbol from cin (stdin)
//
/////////////////////////////////////////////////

Token getSymbol()
{
  char thisSymbol[1024];    // a temporary string to store the input symbol

  // get the next symbol (all characters up to the next white space)
  cin >> thisSymbol;

  if ( strcmp( thisSymbol, "bye" ) == 0 ) 
    exit( 0 );		// exit the program immediately.
  else if ( strcmp( thisSymbol, "zero" ) == 0 )
    return TOKEN_ZERO;
  else if ( strcmp( thisSymbol, "one" ) == 0 )
    return TOKEN_ONE;
  else if ( strcmp( thisSymbol, "two" ) == 0 )
    return TOKEN_TWO;
  else if ( strcmp( thisSymbol, "three" ) == 0 )
    return TOKEN_THREE;
  else if ( strcmp( thisSymbol, "four" ) == 0 )
    return TOKEN_FOUR;
  else if ( strcmp( thisSymbol, "five" ) == 0 )
    return TOKEN_FIVE;
  else if ( strcmp( thisSymbol, "six" ) == 0 )
    return TOKEN_SIX;
  else if ( strcmp( thisSymbol, "seven" ) == 0 )
    return TOKEN_SEVEN;
  else if ( strcmp( thisSymbol, "eight" ) == 0 )
    return TOKEN_EIGHT;
  else if ( strcmp( thisSymbol, "nine" ) == 0 )
    return TOKEN_NINE;
  else if ( strcmp( thisSymbol, "plus" ) == 0 )
    return TOKEN_PLUS;
  else if ( strcmp( thisSymbol, "minus" ) == 0 )
    return TOKEN_MINUS;
  else
    // the token type is unknown to the system
    return TOKEN_UNKNOWN;
}