#include<iostream>
#include<algorithm>
#include<vector>

using namespace std;

long long binSearch(long long* arr, long long N, long long K);
bool possible(long long middle, long long *arr, long long N, long long K);

vector<long long> v;
int main() {
	int N, K;
	cin >> N >> K;

	long long * arr = new long long[K];
	long long sum = 0;
	for (int i = 0; i < K; i++)
		cin >> arr[i];

	cout << binSearch(arr, N, K) << endl;
	for (int z : v) {
		cout << z + 1 << endl;
	}
	system("pause");
	return 0;
}

long long binSearch(long long * arr, long long N, long long K)
{
	long long left = 0;
	long long right = N + 1;
	while (left != right - 1) {
		long long middle = (left + right) / 2;
		if (possible(middle, arr, N, K))
			left = middle;
		else
			right = middle;
	}
	if (left == right)
		return 0;
	return left;
}

bool possible(long long middle, long long * arr, long long N, long long K)
{
	if (middle == 0)
		return false;
	long long k = 0;

	for (long long i = 0; i < K; i++)

		k += (arr[i] / middle);

	if (k >= N)
	{
		v.clear();
		for (long long i = 0; i < K; i++)
		{
			for (long long j = 0; j < arr[i] / middle; j++)
				v.push_back(i);
		}
	}
	return (k >= N) ? true : false;
}