#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target ("avx2")

#include <stdio.h>

using Int = long long;

constexpr Int MO = 1000000007;

int K, N;
int X[100010];

int dp[100010];

int main() {
  scanf("%d", &K);
  scanf("%d", &N);
  for (int i = 0; i < N; ++i) {
    scanf("%d", &X[i]);
  }
  X[N] = K + 1;
  dp[0] = 1;
  for (int x = 1; x <= K; ++x) {
    Int tmp = 0;
    for (int i = 0; X[i] <= x; ++i) {
      tmp += dp[x - X[i]];
    }
    dp[x] = tmp % MO;
  }
  printf("%d\n", dp[K]);
  return 0;
}