# include <cstdlib>
# include <iostream>

using namespace std;

int main ( )
//
//  PRECEDENCE.CPP
//  This program demonstrates how the evaluation of a formula
//  is done using precedence of operators, and how that precedence
//  can be changed by using parentheses.
{
  int a = 10;
  int b = 20;
  int c = 30;
  int d = 40;
  int m, n, o, p, q;

  cout << "\n";
  cout << "PRECEDENCE:\n";
  cout << "  How many ways can we interpret a formula?\n";
  cout << "\n";
  cout << "  Original formula is a + b * c + d / 2\n";
  cout << "\n";
  m = a + b * c + d / 2;
  cout << "    a +   b *     c +     d     / 2   = " << m << "\n";
  cout << "\n";
  cout << "  Adding some parentheses yields:\n";
  cout << "\n";
  n = ( ( a + b * c ) + d ) / 2;
  cout << "( ( a +   b *     c ) +   d )   / 2   = " << n << "\n";
  o = ( a + b ) * ( c + d ) / 2;
  cout << "  ( a +   b ) * ( c +     d )   / 2   = " << o << "\n";
  p = ( a + b * ( c + d ) ) / 2;
  cout << "  ( a +   b * (   c +     d ) ) / 2   = " << p << "\n";
  cout << "\n";
  cout << "  How the formula is actually interpreted:\n";
  cout << "\n";
  q = a + ( b * c ) + ( d / 2 );
  cout << "    a + ( b *     c ) + ( d     / 2 ) = " << q << "\n";

  return 0;
}