#pragma GCC optimize ("O3,unroll-loops")
#pragma GCC target ("avx")

#include <stdio.h>

using Int = long long;

constexpr Int MO = 1000000007;

int K, N;

bool a[100010];
int dp[100010];

int main() {
  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 = 1; y <= K; ++y) {
    Int tmp = 0;
    for (int x = 1; x <= y; ++x) {
      if (a[x]) {
        tmp += dp[y - x];
      }
    }
    dp[y] = tmp % MO;
  }
  printf("%d\n", dp[K]);
  return 0;
}