def max_nesting_depth(exp):
	depth = 0
	max_depth = 0
	for symbol in exp:
		if symbol == '(':
			depth += 1
			max_depth = max(max_depth, depth)
		elif symbol == ')':
			depth -= 1
			if depth < 0: #Unbalanced expression
				return -1
	if depth != 0: #unbalanced expression
		return -1
	return max_depth

print max_nesting_depth("(()())")
print max_nesting_depth("(()")
print max_nesting_depth("(()))")
print max_nesting_depth("(((())))")
print max_nesting_depth("()((((()))))()")