#include <bits/stdc++.h>
int main() {
  int N, M;
  scanf("%d %d", &N, &M);
  int* b = new int[N + 1];
  for (int i = 0; i < N + 1; i++) {
    b[i] = 1;
  }
  for (int i = 0; i < M; i++) {
    int a;
    scanf("%d", &a);
    b[a] = 0;
  }
  long long* n = new long long[N + 1];
  n[0] = 1;
  n[1] = b[1];
  for (int i = 2; i < N + 1; i++) {
    n[i] = b[i] * (n[i - 1] + n[i - 2]);
  }
  int res = n[N] % 1000000007;
  printf("%d", res);
}
