#include <bits/stdc++.h>
int main() {
  int n, m, a[10005], in;
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= n; i++) a[i] = -1;
  for (int i = 1; i <= m; i++) {
    scanf("%d", &in);
    a[in] = 0;
  }
  if (a[1] != 0) a[1] = 1;
  if (a[2] != 0) a[2] = 1 + a[1];
  for (int i = 3; i <= n; i++)
    if (a[i] == -1) a[i] = (a[i - 2] + a[i - 1]) % 1000000007;
  printf("%d", a[n]);
  return 0;
}
