/in/foo.cc: In function 'int main()':
/in/foo.cc:14:23: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
         else if(y < 0 && f((s + 1) / 1000) > 0 || y > 0 && f((s + 1) / 1000) < 0)
                 ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~