#include <cstdio>
#include <cstring>
using namespace std;
typedef double db;const int N = 5e5 + 5;int n, tot = 0, head[N];
db a[N], f[N], g[N];struct Edge {int to, nxt;db val;
} e[N << 1];inline void add(int from, int to, db val) {e[++tot].to = to;e[tot].val = val;e[tot].nxt = head[from];head[from] = tot;
}inline void read(int &X) {X = 0; char ch = 0; int op = 1;for(; ch > '9' || ch < '0'; ch = getchar())if(ch == '-') op = -1;for(; ch >= '0' && ch <= '9'; ch = getchar())X = (X << 3) + (X << 1) + ch - 48;X *= op;
}void dfs1(int x, int fat) {g[x] = 1 - a[x];for(int i = head[x]; i; i = e[i].nxt) {int y = e[i].to;if(y == fat) continue;dfs1(y, x);g[x] *= (g[y] + (1 - g[y]) * (1 - e[i].val));}
}void dfs2(int x, int fat, int inEdge) {if(!fat) f[x] = 1.0;else {db p = g[fat] * f[fat] / (g[x] + (1 - g[x]) * (1 - e[inEdge].val));f[x] = p + (1 - p) * (1 - e[inEdge].val);}for(int i = head[x]; i; i = e[i].nxt) {int y = e[i].to;if(y == fat) continue;dfs2(y, x, i);}
}int main() {
//    freopen("2.in", "r", stdin);
    read(n);for(int x, y, v, i = 1; i < n; i++) {read(x), read(y), read(v);db val = 1.0 * v / 100.0;add(x, y, val), add(y, x, val);}for(int i = 1; i <= n; i++) {int v; read(v);a[i] = 1.0 * v / 100.0;}dfs1(1, 0);dfs2(1, 0, 0);/*    for(int i = 1; i <= n; i++)printf("%f ", f[i]);printf("\n");for(int i = 1; i <= n; i++)printf("%f ", g[i]);printf("\n");    */db ans = 0;for(int i = 1; i <= n; i++)ans += (1 - g[i] * f[i]);printf("%.6f\n", ans);return 0;
}