N,M = map(int,input().split())
a = []
for i in range(M):
    a.append(int(input()))
dp = [0]*(N+1)
dp[1] = 1
if 1 in a:
    dp[2] = 1
    dp[1] = 0
else:
    dp[2] = 2
for i in range(3,N+1):
    if i-1 in a:
        continue
    
    dp[i] = (dp[i-2]+dp[i-1])%1000000007
ans = dp[N]
print(ans)
