n,m= map(int,input().split())
c = [True]*(n+1)
for _ in range(m):
    c[int(input())] = False
d = [0]*(n+1)
if c[1] : d[1] = 1
if c[2] : d[2] = d[1] + 1
for i in range(3,n+1):
    if c[i] :
        d[i] = ( d[i-1] + d[i-2] ) % 1000000007
print(d[n])