n,m = map(int, input().split())
a = [int(input()) for _ in range(m)]
mod = 1000000007
fib = [1,1,2]
for i in range(3,n+1):
    fib.append((fib[i-2]+fib[i-1])%mod)
ans = 0
ans += fib[a[0]-1]

for i in range(1,m):
    if (a[i]-a[i-1]!=1):
        ans *= fib[a[i]-a[i-1]-2]
        ans %= mod
    else:
        print(0)
        exit()
ans *= fib[n-a[m-1]-1]
print(ans%mod)