a = int(input())
b = str(input())
num = 0
while ")(" in b:
  b = b.replace(")(", ")+(")
while "()" in b:
  b = b.replace("()", "(1)")
while "((" in b or "))" in b:
  b = b.replace("((", "", 1)
  b = b.replace("))", ")+1)", 1)
while "1" in b:
  num += 1
  b = b.replace("1", "", 1)
print(num)

# a = int(input())
# b = input()
# count_open_bracket = 0
# count_close_bracker = 0
# result = 0
# for i in b:
#     if i == "(":
#         count_open_bracket+=1
#     if i == ")":
#         count_close_bracker+=1
#         if count_open_bracket > 0:
#             count_close_bracker -= 1
#             count_open_bracket -= 1
#             result += 1
# print(result)