#include <bits/stdc++.h>
using namespace std;
const int maxn = 200020;
int n;
long long l[maxn], t[maxn];
long long ans;
vector<long long> a;
long long ti;
int main() {
  cin >> n >> ti;
  for (int i = 1; i <= n; i++) scanf("%d", &l[i]);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &t[i]);
    if (t[i] < l[i]) {
      printf("-1");
      return 0;
    }
  }
  long long last = 0, now = 0;
  for (int i = 1; i <= n; i++) {
    if (last > l[i]) {
      last -= l[i];
      now += l[i];
      continue;
    }
    l[i] -= last;
    t[i] -= last;
    now += last;
    last = 0;
    if (l[i] << 1 < t[i]) {
      now += l[i] << 1;
      continue;
    }
    long long x = ((l[i] << 1) - t[i] + ti - 1) / ti;
    long long nowx = now;
    long long final = (((l[i]) << 1) - t[i]) % ti;
    last = (ti - final) % ti;
    ans += x;
    now += t[i];
    if (ans > 100000) {
      continue;
    }
    nowx += t[i] - (x * ti - last);
    while (x--) {
      a.push_back(nowx);
      nowx += ti;
    }
  }
  cout << ans << endl;
  if (ans <= 100000) {
    for (int i = 0; i < a.size(); i++) printf("%I64d ", a[i]);
  }
}
