#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <string>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <stdio.h>
using namespace std;
#define int long long
__int128_t MOD = 100000000;

signed main() {
	MOD = 10 * MOD * MOD + 7;
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N, M;
	cin >> N >> M;
	vector<int> A(N, 0);
	A[0] = 1;
	vector<int> X(M);
	for (int i = 0; i < M; i++) {
		cin >> X[i];
	}
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < M; j++) {
			if (i + X[j] < N) {
				A[i + X[j]] = ((__int128_t)A[i + X[j]] + (__int128_t)A[i]) % MOD;
			}
		}
	}
	cout << A[N - 1] << endl;
}