#include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#include <cstdio>
using namespace std;
#define rig register int
#define getcha() (SS == TT && (TT = (SS = BB) + fread(BB, 1, 1 << 20, stdin), SS == TT) ? EOF : *SS++)
#define isint(a) ((a >= '0') && (a <= '9'))
char BB[1 << 20], *SS = BB, *TT = BB;
#define ll long long
#define swwap(a, b) (a ^= b, b ^= a, a ^= b)
#define minn(a, b) (a > b ? b : a)
inline ll read() {
    ll s = 0;
    char ch = getcha();

    while (!isint(ch))
        ch = getcha();

    while (isint(ch))
        s = (s << 3) + (s << 1) + (ch ^ 48), ch = getcha();

    return s;
}
const int maxn = 250005;
const long long inf = 1000000000009;
struct node {
    int x, y, h, rtx, rty;
} u[maxn];
struct bian {
    int to, ne, w;
} ee[maxn << 1];
int cnt;
inline void add(int fr, int to, int w) {
    ee[++cnt].to = to, ee[cnt].ne = u[fr].h, ee[cnt].w = w, u[fr].h = cnt;
}
struct merheap {
    long long v;
    int sum, d, ls, rs;
} em[maxn << 5];
int tot;
int merge(int a, int b) {
    if (!a || !b)
        return a | b;

    if (em[a].v > em[b].v)
        swwap(a, b);

    if (em[a].v == em[b].v)
        em[a].sum += em[b].sum, b = merge(em[b].ls, em[b].rs);

    em[a].rs = merge(em[a].rs, b);

    if (em[em[a].rs].d > em[em[a].ls].d)
        swwap(em[a].ls, em[a].rs);

    em[a].d = em[em[a].rs].d + 1;
    return a;
}
inline int ne(long long v, int sum) {
    em[++tot].v = v, em[tot].sum = sum, em[tot].d = 1;
    return tot;
}
long long ans = 0;
inline void pop(int a, int b, long long d) {
    while (u[a].rtx && u[b].rty) {
        long long v = em[u[a].rtx].v, vv = em[u[b].rty].v;

        if (v + vv - 2 * d >= 0)
            return;

        int sum = minn(em[u[a].rtx].sum, em[u[b].rty].sum);
        ans += sum * (v + vv - 2 * d);
        em[u[a].rtx].sum -= sum, em[u[b].rty].sum -= sum;

        if (!em[u[a].rtx].sum)
            u[a].rtx = merge(em[u[a].rtx].ls, em[u[a].rtx].rs);

        if (!em[u[b].rty].sum)
            u[b].rty = merge(em[u[b].rty].ls, em[u[b].rty].rs);

        u[a].rtx = merge(u[a].rtx, ne(-vv + 2 * d, sum)), u[b].rty = merge(u[b].rty, ne(-v + 2 * d, sum));
    }
}
void dfs(int x, int fa, long long d) {
    if (u[x].y)
        ans += inf * u[x].y, u[x].rty = ne(d - inf, u[x].y);

    if (u[x].x)
        u[x].rtx = ne(d, u[x].x);

    for (rig i = u[x].h; i; i = ee[i].ne) {
        if (ee[i].to == fa)
            continue;

        dfs(ee[i].to, x, d + ee[i].w);
        pop(x, ee[i].to, d), pop(ee[i].to, x, d);
        u[x].rtx = merge(u[x].rtx, u[ee[i].to].rtx), u[x].rty = merge(u[x].rty, u[ee[i].to].rty);
    }
}
int main() {
    int n = read();

    for (rig i = 1, u, v, w; i < n; ++i)
        u = read(), v = read(), w = read(), add(u, v, w), add(v, u, w);

    for (rig i = 1, tmp; i <= n; ++i) {
        u[i].x = read(), u[i].y = read();
        tmp = minn(u[i].x, u[i].y);
        u[i].x -= tmp, u[i].y -= tmp;
    }

    dfs(1, 0, 0);
    printf("%lld\n", ans);
    return 0;
}