#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 5;
const int MOD = 1e9 + 7;
void solve() {
  int n, m;
  cin >> n >> m;
  vector<int> a(n), b(m + 1), la(m + 1);
  for (int i = 0; i < n; ++i) cin >> a[i];
  for (int i = 1; i < m + 1; ++i) cin >> b[i];
  int mid = 0, l = 0, r = n - 1, ans = -1;
  while (l <= r) {
    mid = (l + r) / 2;
    for (int i = 0; i < m + 1; ++i) la[i] = -1;
    for (int i = 0; i < mid + 1; ++i) {
      if (a[i] != 0) la[a[i]] = i;
    }
    int p = 0, ctr = 0;
    for (int i = 0; i < mid + 1; ++i) {
      if (la[a[i]] != i)
        ctr++;
      else if (ctr >= b[a[i]]) {
        ctr -= b[a[i]];
        p++;
      } else
        break;
    }
    if (p == m) {
      ans = mid + 1;
      r = mid - 1;
    } else {
      l = mid + 1;
    }
  }
  cout << ans;
}
int main() {
  int t = 1;
  while (t--) solve();
  return 0;
}
