/in/foo.cc: In function 'int main()':
/in/foo.cc:33:10: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
       if (w[e[j].v]>max2)if (w[e[j].v]>=max1) max2=max1,max1=w[e[j].v]; else max2=w[e[j].v];
          ^
/in/foo.cc:23:38: warning: iteration 200004 invokes undefined behavior [-Waggressive-loop-optimizations]
     for(int i=1;i<=200005;++i)head[i]=0,e[i].next=0;
                               ~~~~~~~^~
/in/foo.cc:23:18: note: within this loop
     for(int i=1;i<=200005;++i)head[i]=0,e[i].next=0;
                 ~^~~~~~~~