/in/foo.cc: In function 'int check(int, int)':
/in/foo.cc:29:17: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
     if(lu != -1 && rv == -1 || ru != -1 && lv == -1) return 0;
        ~~~~~~~~~^~~~~~~~~~~
/in/foo.cc:30:17: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
     if(lv != -1 && ru == -1 || rv != -1 && lu == -1) return 0;
        ~~~~~~~~~^~~~~~~~~~~