n,m = map(int,input().split())
a = list(int(input()) for i in range(m))

mod = 1000000007
b = [0]*(m + 1)

b[0] = a[0] - 1
b[m] = n - a[m - 1] - 1

for i in range(1,m):
    b[i] = a[i] - a[i-1] - 2

b.sort()
ans = 1
if b[0] == -1:
    ans = 0
else:
    pattern = [0]*(b[m]+1)
    pattern[0] = 1
    pattern[1] = 1
    for i in range(2,b[m]+1):
        pattern[i] = pattern[i-1] + pattern[i-2]
    for i in range(m + 1):
        ans *= pattern[b[i]]

print(ans % mod)
