#include <bits/stdc++.h>
using namespace std;
template <typename T>
bool get_int(T &x) {
  char t = getchar();
  bool neg = false;
  x = 0;
  for (; (t > '9' || t < '0') && t != '-' && t != EOF; t = getchar())
    ;
  if (t == '-') neg = true, t = getchar();
  if (t == EOF) return false;
  for (; t <= '9' && t >= '0'; t = getchar()) x = x * 10 + t - '0';
  if (neg) x = -x;
  return true;
}
template <typename T>
void print_int(T x) {
  if (x < 0) putchar('-'), x = -x;
  short a[20] = {}, sz = 0;
  while (x > 0) a[sz++] = x % 10, x /= 10;
  if (sz == 0) putchar('0');
  for (int i = sz - 1; i >= 0; i--) putchar('0' + a[i]);
}
const int inf = 0x3f3f3f3f;
const long long Linf = 1ll << 61;
const double pi = acos(-1.0);
const int maxn = 1000111;
int n, m, hp[maxn], sum, ans;
int a[maxn];
int main() {
  (get_int(n) && get_int(m));
  vector<int> vs;
  for (int i = 1; i <= m; i++) {
    get_int(hp[i]);
    sum += hp[i];
    if (i != m && sum % n) vs.push_back(sum % n);
  }
  ans = (sum + n - 1) / n;
  vs.push_back(0);
  vs.push_back(n);
  sort(vs.begin(), vs.end());
  vs.erase(unique(vs.begin(), vs.end()), vs.end());
  for (int i = 1; i < (int)vs.size(); i++) a[i] = vs[i] - vs[i - 1];
  printf("%d\n", ans);
  for (int i = 1; i <= m; i++) printf("%d ", a[i]);
  puts("");
  int cur = 1;
  for (int i = 1; i <= ans; i++) {
    for (int j = 1; j <= m; j++) {
      hp[cur] -= a[j];
      printf("%d ", min(cur, m));
      while (cur <= m && hp[cur] <= 0) cur++;
    }
    puts("");
  }
  if (cur <= m) puts("baojing");
  return 0;
}
