import bisect
M = 1000000007

# def dfs(i):
#     if i >= n - 1:
#         return 1
#     if dp[i] is not None:
#         return dp[i]
#     if i <= maxv and a[bisect.bisect_left(a, i)] == i:
#         dp[i] = 0
#         return 0
#     r = (dfs(i + 1) + dfs(i + 2)) % M
#     dp[i] = r
#     return r

n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]
a.sort()
maxv = m and max(a) or -1
# dp = [None] * n
# print(dfs(0) % M)

dp = [1] * (n + 2)
for i in range(n - 2, -1, -1):
    if i <= maxv and a[bisect.bisect_left(a, i)] == i:
        dp[i] = 0
    else:
        dp[i] = (dp[i + 1] + dp[i + 2]) % M

print(dp[0] % M)
