#include <iostream>
using namespace std;
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
const int mod = 1000000007;
int K, N, X[100009]; long long dp[100009];
int main() {
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	cin >> K >> N;
	int mx = 0;
	for (int i = 0; i < N; ++i) {
		cin >> X[i];
		if (X[i] == i + 1) mx = i + 1;
	}
	if (mx >= K - 1) {
		int ans = 1;
		for (int i = 1; i < K; ++i) {
			ans = 2 * ans % mod;
		}
		if (mx == K - 1) --ans;
		cout << ans << endl;
		return 0;
	}
	dp[0] = 1;
	for (int i = 1; i <= K; ++i) {
		for (int j = 0; j < N && X[j] <= i; ++j) {
			dp[i] += dp[i - X[j]];
		}
		dp[i] %= mod;
	}
	cout << dp[K] << endl;
	return 0;
}