n, m = map(int, input().split(' '))
a = []
for i in range(m):
    a.append(int(input()))


s = [0] * (n + 1)
s[0] = 1
for i in range(n):
    j = i + 1
    while(j <= min(n, i + 2)):
        if j not in a:
            s[j] += s[i]
            s[j] = int(s[j] % 1000000007)
        j += 1

print(s[n])
