/in/foo.cc: In function 'Node* build(int, int)':
/in/foo.cc:84:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid = l + r >> 1;
            ~~^~~
/in/foo.cc: In function 'int LCQ(int, int)':
/in/foo.cc:154:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int mid = L + R >> 1;
             ~~^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:196:15: warning: NULL used in arithmetic [-Wpointer-arith]
   if (opt[0]==NULL) break;
               ^~~~