MOD = 10**9 + 7
N, M = map(int, input().split())
stairs = [0]*(N+1)
for _ in range(M):
    stairs[int(input())] = 1
ans = [0]*(N+1)
ans[1] = 1 if stairs[1] == 0 else 0
ans[2] = 1 + ans[1] if stairs[2] == 0 else ans[1]
for i in range(3,N+1):
    if stairs[i] == 1:
        ans[i] = 0
        continue
    ans[i] = (ans[i-1] + ans[i-2]) % MOD
print(ans[N])