#include <bits/stdc++.h>
using namespace std;
unsigned int memo[100001];
unsigned int memb[100000];
int length = 0;
void bfib(int n) {
  bool bf = false;
  for (int i = 0; i < length; ++i) {
    if (memb[i] == 1) {
      bf = true;
    }
    if (memb[i] == n) {
      memo[n] = 0;
      return;
    }
  }
  if (n == 1) {
    memo[n] = 1;
    return;
  }
  if (n == 2) {
    if (bf == true) {
      memo[n] = 1;
    } else {
      memo[n] = 2;
    }
    return;
  } else {
    memo[n] = (memo[n - 1] + memo[n - 2]) % 1000000007;
    return;
  }
}
int main(void) {
  int n, nb, buf;
  n = nb = buf = 0;
  scanf("%d %d", &n, &nb);
  length = nb;
  for (int i = 0; i < nb; ++i) {
    scanf("%d", &buf);
    memb[i] = buf;
  }
  for (int i = 0; i <= n; ++i) {
    bfib(i);
  }
  cout << memo[n];
  return 0;
}
