x amp；amp;y ?x：y

xamp;amp;y?x:y;

x;

y

lt;gt;?lt;gt; ;:lt;gt;?

x?y?

xamp;amp;y?x?y?amp;amp;x?yc0?0xamp;amp;yx?y0 ?x?y?0?

x?y?0?xxx?y0?yy