#include<iostream>
#include<ctime>
#include<cstring>
using namespace std;

const int MAXN = 2 * 1e5 + 5;
const int INF = 0x3f3f3f3f;
struct node{
    int to, nxt;
}e[MAXN << 1];
int h[MAXN], tot = 0;
char color[MAXN];
int n, c[MAXN];
int f[MAXN][2][2];

void add(int x, int y){
    e[++ tot] = {y, h[x]};
    h[x] = tot;
}
/*
fa
 \ 
  u (blue)
  /\ 
 v  v
f[u][0 / 1][0 / 1]
u | is blue or not | change or not
*/
void dfs(int u, int fa){
    memset(f[u], INF, sizeof(f[u]));
    if(color[u] == 'Y'){
        f[u][1][0] = 0;
        f[u][1][1] = c[u];
    }
    f[u][0][0] = 0;
    f[u][0][1] = c[u];
    for(int i = h[u];i;i = e[i].nxt){
        int v = e[i].to;
        if(v == fa) continue;
        dfs(v, u);
        int tmp[2][2]; memset(tmp, INF, sizeof(tmp));
        for(int x = 0;x < 2;++ x){
            for(int y = 0;y < 2;++ y){
                if(f[u][x][y] == INF) continue;
                for(int a = 0;a < 2;++ a){
                    if(a == 0 && y == 0) continue;
                    for(int b = 0;b < 2;++ b){
                        if(f[v][a][b] == INF) continue;
                        int nw = x | (a & b);
                        tmp[nw][y] = min(tmp[nw][y], f[u][x][y] + f[v][a][b]);
                    }
                }
            }
        }
        memcpy(f[u], tmp, sizeof(tmp));
    }
}

int main(){
    freopen("Influencers.in", "r", stdin);
    freopen("Influencers.out", "w", stdout);
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n;
    for(int i = 1;i < n;++ i){
        int u, v; cin >> u >> v;
        add(u, v), add(v, u);
    }

    string s; cin >> s;
    for(int i = 1;i <= n;++ i){
        color[i] = s[i - 1];
    }

    for(int i = 1;i <= n;++ i){
        cin >> c[i];
    }

    memset(f, INF, sizeof(f));
    dfs(1, 0);

    cout << min(f[1][1][0], f[1][1][1]) << '\n';

    // cerr << "Time : " << 1.0 * clock() / CLOCKS_PER_SEC << "s \n";
    return 0;
}