#pragma GCC optimize ("Ofast,unroll-loops")
#pragma GCC target ("avx")
#include <bits/stdc++.h>
using namespace std;
using lint = long long;
template<class T = int> using V = vector<T>;
template<class T = int> using VV = V< V<T> >;

#ifdef __linux__
#define getchar getchar_unlocked
#define putchar putchar_unlocked
#endif
int read_int(){int c,r;while((c=getchar())<48);r=c-48;while((c=getchar())>47)r=r*10+c-48;return r;}
void write_int(int x){int b[10],*p=b;do*p++=48+x%10,x/=10;while(x);do putchar(*--p);while(p>b);}

constexpr int mod = 1e9 + 7;

constexpr int N = 1e5;
int dp[N + 1], f[N + 1];

int main() {
  int k = read_int();
  int n = read_int();
  for (int i = 0; i < n; ++i) {
    f[read_int()] = 1;
  }
  dp[0] = 1;
  for (int j = 0; j < k; ++j) {
    for (int i = 0; j + i <= k; ++i) {
      dp[j + i] += f[i] * dp[j];
      dp[j + i] -= (dp[j + i] >= mod) * mod;
    }
  }
  cout << dp[k] << '\n';
}