#pragma GCC optimize ("Ofast,unroll-loops")
#pragma GCC target ("avx")

#include <stdio.h>

int main() {
  constexpr int MO = 1000000007;
  int K, N;
  int a[100010] = {};
  int dp[100010] = {};
  scanf("%d", &K);
  scanf("%d", &N);
  for (int i = 0; i < N; ++i) {
    int x;
    scanf("%d", &x);
    a[x] = 1;
  }
  dp[0] = 1;
  for (int y = 0; y < K; ++y) {
    const int c = dp[y];
    for (int x = 1; x <= K - y; ++x) {
      dp[y + x] -= ((dp[y + x] += a[x] * c) >= MO) * MO;
    }
  }
  printf("%d\n", dp[K]);
  return 0;
}