// Hydro submission #67471e4e9592d6097b87066e@1732714063322
#include<bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
const int N = 1e5 + 10;
vector<int> v[N];
int rt[N];
void dfs(int x, int fa){
    rt[x] = fa;
    for(int y : v[x]){
        if(y == fa) continue;
        dfs(y, x);
    }
}
int n;
struct Node{
    int a, b, id, res;
    bool operator < (const Node &A) const {
        if(a > b && A.a <= A.b) return 1;//回血在前
        if(a <= b && A.a > A.b) return 0;
        if(a > b && A.a > A.b) return b <= A.b;
        else return a > A.a;
    }
}p[N];
bool vis[N];
int ans[N];
priority_queue<Node> q;
int find(int x) {
    if(vis[rt[x]]) return rt[x] = find(rt[x]);
    return rt[x];
}
signed main(){
    freopen("tree.in", "r", stdin);
    freopen("tree.out", "w", stdout);
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    cin >> n;
    for(int i = 2; i <= n; i++){
        int a, b;
        cin >> a >> b;
        p[i] = Node{a, b, i, 0};
        q.push(p[i]);
    }
    for(int i = 1; i < n; i++){
        int x, y;
        cin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    dfs(1, 0);
    int cnt = 0;
    while(!q.empty()){
        auto now = q.top();
        q.pop();
        // cout << now.id << endl;
        if(vis[now.id] || now.res != ans[now.id]) continue;
        vis[now.id] = 1;
        int x = now.id, fax = find(now.id);
        int a = p[fax].a;
        p[fax].a = max(p[fax].a, p[fax].a - p[fax].b + p[x].a);
        p[fax].b = p[fax].b - a - p[x].a + p[x].b + p[fax].a;
        if(fax > 1){
            p[fax].res = ans[fax] = ++cnt;
            q.push(p[fax]);
        }
    }
    cout << p[1].a << endl;
    cerr << 1.0 * clock() / CLOCKS_PER_SEC << endl;
    return 0;
}