#include <bits/stdc++.h>
using namespace std;
inline char read() {
  static const int IN_LEN = 1000000;
  static char buf[IN_LEN], *s, *t;
  return (s == t               ? t = (s = buf) + fread(buf, 1, IN_LEN, stdin),
          (s == t ? -1 : *s++) : *s++);
}
template <class T>
inline void read(T &x) {
  static bool iosig;
  static char c;
  for (iosig = false, c = read(); !isdigit(c); c = read()) {
    if (c == '-') iosig = true;
    if (c == -1) return;
  }
  for (x = 0; isdigit(c); c = read()) x = ((x + (x << 2)) << 1) + (c ^ '0');
  if (iosig) x = -x;
}
const int OUT_LEN = 10000000;
char obuf[OUT_LEN], *ooh = obuf;
inline void print(char c) {
  if (ooh == obuf + OUT_LEN) fwrite(obuf, 1, OUT_LEN, stdout), ooh = obuf;
  *ooh++ = c;
}
template <class T>
inline void print(T x) {
  static int buf[30], cnt;
  if (x == 0)
    print('0');
  else {
    if (x < 0) print('-'), x = -x;
    for (cnt = 0; x; x /= 10) buf[++cnt] = x % 10 + 48;
    while (cnt) print((char)buf[cnt--]);
  }
}
inline void flush() { fwrite(obuf, 1, ooh - obuf, stdout); }
const int N = 1000005;
int n, m, sum, a[N], b[N];
int main() {
  read(n), read(m);
  for (int i = 1; i <= m; ++i)
    read(a[i]), b[i] = (b[i - 1] + a[i]) % n, sum += a[i];
  sort(b + 1, b + m), b[m] = n;
  for (int i = m; i > 1; --i) b[i] -= b[i - 1];
  print((sum - 1) / n + 1), print('\n');
  for (int i = 1; i <= m; ++i) print(b[i]), print(' ');
  print('\n');
  int j = 1;
  for (int i = 1; i <= m; ++i) {
    while (a[i] > 0) {
      a[i] -= b[j], print(i);
      if (j == m)
        print('\n'), j = 1;
      else
        print(' '), ++j;
    }
  }
  if (j > 1)
    while (j <= m) print(m), print(' '), ++j;
  return flush(), 0;
}
