n,m=map(int,input().split())
use=[0]
ans=1
for i in range(m):
    use.append(int(input()))
use.append(n)
print(use)
if N>=2:        
    lists=[1,2]

    for i in range(n-2):
        lists.append((lists[-1]+lists[-2])%1000000007)

    
    for i in range(m+1):
    
        if use[i+1]-use[i]==1 and i>=1:
            ans=0
            break
        else:
            ans=(ans*lists[int(use[i+1]-use[i]-2)])%1000000007
            
            
    print(ans)
elif N==1:
    print(1)
