/in/foo.cc: In function 'bool cmp(node, node)':
/in/foo.cc:17:27: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
 { return a.a<b.a||a.a==b.a&&a.b<b.b;}
                   ~~~~~~~~^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:42:9: warning: unused variable 'x' [-Wunused-variable]
  double x;
         ^