/* Parentheses

You may have heard of the programming language Lisp, or its more modern 
descendant, Scheme. One inescapable fact of Lisp programming is that you 
must use a lot of parentheses.

Suppose that you've just started learning Lisp. You keep writing expressions 
in which you forget to close some of the parenthesis. Write a program that 
validates that for every left-parenthesis character '(' input to your program, 
there is a corresponding right-parenthesis character ')'. 

Hint: All inputs will be a single line of characters terminated with the 
newline character.

============= START OF SAMPLE RUN ========================
---------------- START OF INPUT --------------------------
(+ 7 (* 5 (+ 1 4)))
----------------- END OF INPUT ---------------------------
---------------- START OF OUTPUT -------------------------
Valid Input
----------------- END OF OUTPUT --------------------------
============= END OF SAMPLE RUN ==========================


============= START OF SAMPLE RUN ========================
---------------- START OF INPUT --------------------------
((((())))
----------------- END OF INPUT ---------------------------
---------------- START OF OUTPUT -------------------------
Invalid Input
----------------- END OF OUTPUT --------------------------
============= END OF SAMPLE RUN ==========================


============= START OF SAMPLE RUN ========================
---------------- START OF INPUT --------------------------
)(
----------------- END OF INPUT ---------------------------
---------------- START OF OUTPUT -------------------------
Invalid Input
----------------- END OF OUTPUT --------------------------
============= END OF SAMPLE RUN ==========================


============= START OF SAMPLE RUN ========================
---------------- START OF INPUT --------------------------
(cdr (car '((peas carrots tomatoes) (pork beef chicken))))
----------------- END OF INPUT ---------------------------
---------------- START OF OUTPUT -------------------------
Valid Input
----------------- END OF OUTPUT --------------------------
============= END OF SAMPLE RUN ==========================

*/

#include <stdio.h>

int main(const int argc, const char* argv[])
{
	int c;
	unsigned long left = 0;
	unsigned long right = 0;

	do
	{
		c = getchar();
		if (c == '(')
		{
			left++;
		}
		else if (c == ')')
		{
			right++;
		}
		if(right>left)
			break;
	}
	while (c != '\n' && c != EOF);

	if (left == right)
	{
		printf("Valid Input\n");
	}
	else
	{
		printf("Invalid Input\n");
	}

	system("pause");
	return 0;
}