/*	Author:         R.P. Patillo
        Instructor:     Dr. Ames
        Due Date:       Oct. 23, 2008
        Complilation:   g++ WFFcatcher.cpp -o WFFcatcher.out
        Execution:      ./WFFcatcher.out
*/

#include <iostream>

using namespace std;


//----------------------
// WFF Catcher
//----------------------

bool WFFcatch()
{
    char ch = ' ';
    char prevch1 = ' ';
    char prevch2 = ' ';
    bool WFF = true;

    if(WFF)
    {
	cin.get(ch);
	if(ch == 'p' || ch == 'q' || ch == 'r' || ch == 's')
	{
	    if(prevch1 == 'p' || prevch1 == 'q' || prevch1 == 'r' || prevch1 == 's' || prevch1 == ' ')
	    {
		if(prevch2 == 'C' || prevch2 == 'A' || prevch2 == 'K' || prevch2 == 'E')
			return WFFcatch();
		else
		{
			return false;
		}				
	    }	    

	    else if(prevch1 == 'N')
		return WFFcatch();

	    else if(prevch1 == 'C' || prevch1 == 'A' || prevch1 == 'K' || prevch1 == 'E')
	    {
		prevch2 = prevch1;
		ch = prevch1;
		cout << "*" << ch << "*" << prevch1 << "*" << prevch2;
		return WFFcatch();
	    }

	    else if(ch == '\n')
	    {
		if(prevch1 == 'p' || prevch1 == 'q' || prevch1 == 'r' || prevch1 == 's')
		    return true;

		else
		{
		    return false;
		    WFF = false;
		}
	    }

	    else
		ch = prevch1;
		cout << ch << "***" << prevch1;
	}
	else if(ch == 'N')
	{
	    ch = prevch1;
	    return WFFcatch();
	}
	
	else if(ch == 'C' || ch == 'A' || ch == 'K' || ch == 'E')
	{
	    ch = prevch1;
	    cout << ch << "******" << prevch1;
	    return WFFcatch();
	}

	else
	    return false;
	    WFF = false;
    }

    else if(ch == '\n')
    {
         if(prevch1 == 'p' || prevch1 == 'q' || prevch1 == 'r' || prevch1 == 's')
              return true;

         else
         {
              return false;
              WFF = false;
         }
    }


}

//----------------------------------------------------

int main ()
{
    char ch, prevch1, prevch2;

    cout << "Enter a well-formed formula: ";

    cin.get(ch);
    ch = prevch1;
    cout << prevch1;

    WFFcatch();

    if (WFFcatch() == true)
	cout << "well formed" << endl;

    else if(WFFcatch() == false)
	cout << "error" << endl;

    return 0;
}