#include #include

using namespace std;

const int N = 1010;

struct Node { int father, size, sum; double avg; }nodes[N];

int n, root;

int find() //找权值最大的根节点 { double avg = 0; int res = -1; for(int i = 1; i <=n; i++) if(i != root && avg < nodes[i].avg) { avg = nodes[i].avg; res = i; } return res;
}

int main() { int res = 0; cin >> n >> root; for(int i = 1; i <= n; i++) { auto &nd = nodes[i]; cin >> nd.sum; nd.size = 1; nd.avg = nd.sum; res += nd.sum; //初始赋值 每个数乘一加一块，所有数的和 } for(int i = 0, a, b; i < n - 1;i++) { cin >> a >> b; nodes[b].father = a; }

for(int i = 0; i < n - 1; i++)
{
    int ver = find();
    int f = nodes[ver].father;
    res += nodes[ver].sum * nodes[f].size;
    nodes[ver].avg = -1;
    for(int j = 1; j <= n; j++)
        if(nodes[j].father == ver)
            nodes[j].father = f;
    nodes[f].sum += nodes[ver].sum;
    nodes[f].size += nodes[ver].size;
    nodes[f].avg = (double)nodes[f].sum / nodes[f].size;
}
cout << res << endl;
return 0;

}