https://adventofcode.com/2015/day/1

Count open and closing parentheses.

>>> :main + "(())\n"
0

>>> :main + "()()\n"
0

>>> :main + "(((\n"
3

>>> :main + "(()(()(\n"
3

>>> :main + "))(((((\n"
3
1

>>> :main + "())\n"
-1
3

>>> :main + "))(\n"
-1
1

>>> :main + ")))\n"
-3
1

>>> :main + ")())())\n"
-3
1

>>> :main + "()())\n"
-1
5