var add_one = function ( n ) {
   return n + 1;
}

var subtract_one = function ( n ) {
   return n - 1;
}

var sum = function ( a, b ) {
   if (b === 0) {
   		return a;
   } else {
   		return sum( add_one( a ), subtract_one ( b ) );
   };
}

var product = function( a, b ) {
	if ( b == 1 ) {
		return a;
	} else {
		return sum( a, product( a, subtract_one(b) ) );
	};
}