#include <bits/stdc++.h>
using namespace std;
template <typename T>
void maxtt(T& t1, T t2) {
  t1 = max(t1, t2);
}
template <typename T>
void mintt(T& t1, T t2) {
  t1 = min(t1, t2);
}
bool debug = 0;
int n, m, k;
string direc = "URDL";
const long long MOD2 = (long long)1000000007 * (long long)1000000007;
long long ln, lk, lm;
void etp(bool f = 0) {
  puts(f ? "YES" : "NO");
  exit(0);
}
void addmod(int& x, int y, int mod = 1000000007) {
  x += y;
  if (x >= mod) x -= mod;
  if (x < 0) x += mod;
  assert(x >= 0 && x < mod);
}
void et(int x = -1) {
  printf("%d\n", x);
  exit(0);
}
long long fastPow(long long x, long long y, int mod = 1000000007) {
  long long ans = 1;
  while (y > 0) {
    if (y & 1) ans = (x * ans) % mod;
    x = x * x % mod;
    y >>= 1;
  }
  return ans;
}
long long gcd1(long long x, long long y) { return y ? gcd1(y, x % y) : x; }
int p[1000035], q[1000035];
void fmain(int tid) {
  scanf("%d%lld", &n, &lk);
  for (int(i) = 1; (i) <= (int)(n); (i)++) {
    p[i] = q[i] = i;
  }
  long long mi = (long long)(n + 1) * n / 2;
  int hf = n / 2;
  long long mx = (long long)(n - hf + 1 + n) * hf;
  if (n & 1) mx += n / 2 + 1;
  if (lk < mi) et();
  mintt(lk, mx);
  long long tar = lk - mi;
  for (int(i) = 1; (i) <= (int)(hf); (i)++) {
    int bg = n + 1 - i;
    if (bg - i <= tar) {
      swap(q[i], q[bg]);
      tar -= bg - i;
    } else {
      swap(q[i], q[i + tar]);
      break;
    }
  }
  printf("%lld\n", lk);
  for (int(i) = 1; (i) <= (int)(n); (i)++) printf("%d ", p[i]);
  puts("");
  for (int(i) = 1; (i) <= (int)(n); (i)++) printf("%d ", q[i]);
  puts("");
}
int main() {
  int t = 1;
  for (int(i) = 1; (i) <= (int)(t); (i)++) {
    fmain(i);
  }
  return 0;
}
