n, m = list(map(int, input().split()))
a = [input() for i in range(m)]
b = []
c = []
total_act = 0
total_act2 = 1
total = 1
b.append(int(a[0]))
for i in range(len(a) - 1):
    b.append(int(a[i + 1]) - int(a[i]) - 1)
for i in range(max(b)):
    total_act3 = total_act2 + total_act
    total_act2 = total_act
    total_act = total_act3
    c.append(total_act)
for i in b:
    total *= c[i - 1]

total *= c[n - int(a[-1]) - 1]
print(total % 1000000007)
