foo.cc: In lambda function:
foo.cc:13:63: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
   13 |         sort(a+1,a+n+1,[&](st a,st b){return a.y>b.y||a.y==b.y&&a.s>b.s;});
      |                                                       ~~~~~~~~^~~~~~~~~