#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int> > ke[105];
int d[105], x[105], y[105], a[105];
int n, m, s, t, module;
void dijkstra() {
  set<pair<int, int> > q;
  for (int u = 1; u <= n; ++u) d[u] = 1000000007;
  d[1] = 0;
  q.insert(make_pair(d[1], 1));
  while (!q.empty()) {
    pair<int, int> top = *(q.begin());
    q.erase(top);
    int u = top.second;
    if (u == n) return;
    for (int i = 0; i < ke[u].size(); ++i) {
      int v = ke[u][i].first;
      int w = ke[u][i].second;
      if (d[v] > d[u] + w) {
        q.erase(make_pair(d[v], v));
        d[v] = d[u] + w;
        q.insert(make_pair(d[v], v));
      }
    }
  }
}
int main() {
  cin >> n >> module;
  for (int i = 2; i <= n - 1; ++i) scanf("%d", &a[i]);
  for (int i = 1; i <= n; ++i) scanf("%d%d", &x[i], &y[i]);
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= n; ++j) {
      if (i != j) {
        ke[i].push_back(make_pair(
            j, module * (abs(x[i] - x[j]) + abs(y[i] - y[j])) - a[j]));
        ke[j].push_back(make_pair(
            i, module * (abs(x[i] - x[j]) + abs(y[i] - y[j])) - a[i]));
      } else {
        ke[i].push_back(make_pair(j, 1000000007));
        ke[j].push_back(make_pair(i, 1000000007));
      }
    }
  }
  s = 1;
  t = n;
  dijkstra();
  if (d[t] == 1000000007)
    printf("-1");
  else
    printf("%d\n", d[t]);
  return 0;
}
