/in/foo.cc: In function 'void splay(int)':
/in/foo.cc:44:38: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
         if(!isroot(y))spin((son[y][0]==x^son[z][0]==y)?x:y);
                             ~~~~~~~~~^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:68:31: warning: unused variable 'a' [-Wunused-variable]
         int u=e[i].u,v=e[i].v,a=e[i].a,b=e[i].b;
                               ^
/in/foo.cc:68:40: warning: unused variable 'b' [-Wunused-variable]
         int u=e[i].u,v=e[i].v,a=e[i].a,b=e[i].b;
                                        ^
/in/foo.cc:65:25: warning: unused variable 'x' [-Wunused-variable]
     sort(e+1,e+m+1);int x;
                         ^