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

int BIG_N = 1000000007;

int main(){
  int K = 0, N = 0;
  std::cin >> K;
  std::cin >> N;
  std::vector<int> X;
  for (int i = 0; i < N; i++){
    int x = 0;
    std::cin >> x;
    X.push_back(x);
  }
  std::vector<int> kaidan(K + 1);
  kaidan[0] = 1;
  for (int k_idx = 0; k_idx < kaidan.size() - 1; k_idx++) {
    if (kaidan[k_idx] == 0) continue;
    int cur = kaidan[k_idx];
    for (auto x: X) {
      if (k_idx + x < kaidan.size()) {
        kaidan[k_idx + x] += cur;
        kaidan[k_idx + x] %= BIG_N;
      }
    }
  }
  // for (auto k : kaidan) {
  //   std::cout << k << std::endl;
  // }

  std::cout << kaidan[kaidan.size() - 1] << std::endl;
}