#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 100000
int max(int a, int b) { return a > b ? a : b; }
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
int *ej[N], eo[N];
void append(int i, int j) {
int o = eo[i]++;
if (o >= 2 && (o & o - 1) == 0)
ej[i] = (int *) realloc(ej[i], o * 2 * sizeof *ej[i]);
ej[i][o] = j;
}
int aa[N];
void sort(int *ii, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;
while (j < k)
if (aa[ii[j]] == aa[i_])
j++;
else if (aa[ii[j]] < aa[i_]) {
tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
i++, j++;
} else {
k--;
tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
}
sort(ii, l, i);
l = k;
}
}
int ds[N];
int find(int i) {
return ds[i] < 0 ? i : (ds[i] = find(ds[i]));
}
int join(int i, int j) {
int a;
i = find(i);
j = find(j);
if (i == j)
return 0;
a = aa[i] + aa[j], aa[i] = aa[j] = max(aa[i], aa[j]);
if (ds[i] > ds[j])
ds[i] = j;
else {
if (ds[i] == ds[j])
ds[i]--;
ds[j] = i;
}
return a;
}
int main() {
static int ii[N];
static char alive[N];
int n, h, i, j, o;
long long ans;
scanf("%d", &n);
for (i = 0; i < n; i++) {
scanf("%d", &aa[i]);
ej[i] = (int *) malloc(2 * sizeof *ej[i]);
}
for (h = 0; h < n - 1; h++) {
scanf("%d%d", &i, &j), i--, j--;
append(i, j), append(j, i);
}
for (i = 0; i < n; i++)
ii[i] = i;
sort(ii, 0, n);
memset(ds, -1, n * sizeof *ds);
ans = 0;
for (h = 0; h < n; h++) {
i = ii[h];
alive[i] = 1;
for (o = eo[i]; o--; ) {
j = ej[i][o];
if (alive[j])
ans += join(i, j);
}
}
printf("%lld\n", ans);
return 0;
}
