#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, M, a;
  scanf("%d %d", &N, &M);
  long dp[N + 1];
  for (int i = 0; i < M; i++) {
    scanf("%d", &a);
    dp[a] = -1;
  }
  dp[0] = 1;
  if (dp[1] == -1) {
    dp[1] = 0;
  } else {
    dp[1] = 1;
  }
  for (int i = 2; i < N + 1; i++) {
    if (dp[i] == -1) {
      dp[i] = 0;
    } else {
      dp[i] = (dp[i - 1] + dp[i - 2]) % 1000000007;
    }
  }
  printf("%ld\n", dp[N]);
}
