hdu1055

#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<queue>
#include<string>
#include<vector>
#define eps 1e-6
#define LL long long
#define LD long double
#define pi acos(-1.0)
#define inf 1<<30
using namespace std;
struct Node{
int idx,next;
}a[1005];
int cnt,n,root,c[1005],num[1005],pre[1005],start[1005];
bool visit[1005];
int addedge(int u,int v){
a[cnt].idx=v;
a[cnt].next=start[u];
return cnt++;
}
int find_root(){
double mmax=0;
int k;
for(int i=1;i<=n;i++)
if(!visit[i]&&(double)c[i]/num[i]>mmax&&i!=root){
mmax=(double)c[i]/num[i];
k=i;
}
return k;
}
void Union(int k,int p){
num[p]+=num[k];
c[p]+=c[k];
for(int i=start[k];i;i=a[i].next)
pre[a[i].idx]=p;
}
int slove(){
int ans=0;
for(int i=1;i<n;i++){
int k=find_root();
visit[k]=true;
int p=pre[k];
while(visit[p]) p=pre[p];
ans+=num[p]*c[k];
Union(k,p);
}
return ans+c[root];
}
int main(){
while(scanf("%d%d",&n,&root)!=EOF&&n+root){
memset(start,0,sizeof(start));
memset(visit,false,sizeof(visit));
for(int i=1;i<=n;i++){
scanf("%d",&c[i]);
num[i]=1;
}
cnt=1;
for(int i=1;i<n;i++){
int u,v;
scanf("%d%d",&u,&v);
start[u]=addedge(u,v);
pre[v]=u;
}
printf("%d\n",slove());
}
return 0;
}