#include "bits/stdc++.h"
using namespace std;
#define pb push_back
#define endl "\n"
#define int long long
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
/* stuff you should look for
* int overflow, array bounds
* special cases (n=1?)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH
* SIMPLIFY THE PROBLEM
* READ THE STATEMENT CAREFULLY
!!! if there is an specified/interesting smth(i.e. constraint) in the statement,
then you must be careful about that
*/
const int N = 1e5 + 5;
int ar[N],par[N],ans=0;
vector<int> v[N],v2[N],vis(N,0);
int find(int a){
if(par[a]==a) return a;
return par[a]=find(par[a]);
}
void unite(int a,int b){
a=find(a),b=find(b);
if(ar[a]>ar[b]) swap(a,b);
par[a]=b;
}
void dfs(int c,int p){
ans += sz(v2[c]) * ar[c];
for(int x:v2[c]){
if(x==p) continue;
dfs(x,c);
}
}
void solve(){
iota(par,par+N,0LL);
int n;
cin >> n;
for(int i=1;i<=n;i++) cin >> ar[i];
for(int i=1;i<n;i++){
int a,b;
cin >> a >> b;
v[a].pb(b);
v[b].pb(a);
}
vector<array<int,2>> xd;
for(int i=1;i<=n;i++) xd.pb({ar[i],i});
sort(all(xd));
for(auto x:xd){
int a = x[1];
vis[a] = 1;
for(int u : v[a]){
if(!vis[u]) continue;
v2[a].pb(find(u));
v2[find(u)].pb(a);
unite(a,u);
}
}
dfs(1,0);
cout << ans << endl;
}
int32_t main(){
cin.tie(0); ios::sync_with_stdio(0);
int t=1;//cin >> t;
while(t--) solve();
return 0;
}
