import java.util.Stack;

public class Dijkstra
{
    public static Integer eval(String[] inp)
    {
	Stack<Integer> operandStk  = new Stack<>();
	Stack<String>  operatorStk = new Stack<>();
	String s;

	for ( int i = 0; i < inp.length; i++ )
	{
	    s = inp[i];
	    System.out.println(">" + s);

	    if ( s.equals("(") )
	    {
		// Do nothing... wait for a ")"
	    }
	    else if ( s.equals(")") )
	    {
		// Eval one bracketed  expression
		int o2 = operandStk.pop();
		int o1 = operandStk.pop();
                String op = operatorStk.pop();

		int r = operate(op, o1, o2);

	        operandStk.push( r ); // Result is operand for next operation
            }
	    else if ( s.equals("x") || s.equals("/") ||
		      s.equals("+") || s.equals("-")     )
                operatorStk.push( s );	              // Save on operatorStk
	    else
                operandStk.push(Integer.parseInt(s)); // Save on operandStk

	    System.out.println("operandStk = " + operandStk);
	    System.out.println("operatorStk = " + operatorStk);
	}

	return operandStk.pop();  // Return result
    }

    public static int operate( String op, int o1, int o2 )
    {

        if ( op.equals("x") )
        {
            System.out.println(">>>" + o1 + " * " + o2);
	    return( o1*o2 );
        }
        else if ( op.equals("/") )
        {
            System.out.println(">>>" + o1 + " / " + o2);
	    return( o1/o2 );
        }
	else if ( op.equals("+") )
	{
            System.out.println(">>>" + o1 + " + " + o2);
            return( o1+o2 );
	}
	else if ( op.equals("-") )
	{
	    System.out.println(">>>" + o1 + " - " + o2);
            return( o1-o2 );
	}
	else
	    return 0;
    }
}