#include <bits/stdc++.h>
using namespace std;
int mark[100005];
long long msum[100005];
long long sum[100005];
int c[100005];
long long cs;
int main() {
  long long ans = 0;
  int i, n, m, x;
  scanf("%d%d", &n, &m);
  for (i = 1; i <= n; ++i) scanf("%d", &c[i]);
  for (i = 1; i <= m; ++i) {
    scanf("%d", &x);
    mark[x] = 1;
  }
  for (i = n; i > 0; --i) {
    sum[i] = sum[i + 1] + c[i];
    msum[i] = msum[i + 1] + c[i] * mark[i];
  }
  for (i = 1; i <= n; ++i)
    if (mark[i])
      ans += c[i] * sum[i + 1];
    else {
      ans += c[i] * msum[i + 1];
      if (!mark[i + 1]) ans += (long long)c[i] * c[i + 1];
      if (i == 1 && !mark[n]) ans += (long long)c[i] * c[n];
    }
  printf("%I64d\n", ans);
  fclose(stdin);
  fclose(stdout);
  return 0;
}
