foo.cc: In function ‘bool cmp(stu, stu)’:
foo.cc:12:39: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
   12 |                         a.zf()==b.zf()&&a.yszf()>b.yszf()
      |                         ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:14:25: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
   13 |                         ||a.zf()==b.zf()&&a.yszf()==b.yszf()
      |                           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   14 |                         &&a.ysgf()>b.ysgf();
      |                         ^~~~~~~~~~~~~~~~~~~