/in/foo.cc: In function 'int main()':
/in/foo.cc:18:28: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   18 |                 if (d == 0 && a[now].dir == 1 || d == 1 && a[now].dir == 0)
      |                     ~~~~~~~^~~~~~~~~~~~~~~~~~