n, m = (int(i) for i in raw_input().split())
a = []
for i in range(m):
    a.append(int(raw_input()))

dp = [0 for i in range(n+2)]
for i in range(n+1):
    if i in a:
        dp[i] = 0
    elif i == 0:
        dp[0] = 1
    elif i == 1:
        dp[1] = 1
    else:
        dp[i] = (dp[i-1] + dp[i-2])

print (dp[n] % 1000000007)
