n, m = list(map(int, input().split()))
b = [-1]
ans = 1

def dfs(top, bot):
    if top == bot:
        return 1
    elif top < bot:
        return 0
    else:
        return dfs(top - 1, bot) + dfs(top - 2, bot)
    
for i in range(m):
    broken = int(input())
    b.append(broken)

b.append(n + 1)
##print (b)

for i in range(len(b) - 1):
    if b[i] + 1 in b:
        ans = 0
        break
    else:
##        print (b[i + 1] - 1, b[i] + 1)
        ans *= dfs(b[i + 1] - 1, b[i] + 1)
        
print(ans%1000000007)
