import math
n, m = [int(i) for i in input().split()]
p = [0 for i in range(n + 1)]
for _ in range(m):
    p[int(input())] = 1
    
a = []
a.append(1)
if 1 in p:
    a.append(0)
else:
    a.append(1)
for i in range(2, n + 1):
    if p[i] == 1:
        a.append(0)
    else:
        a.append((a[i - 2] + a[i - 1]) % 1000000007)
    
print(a[n])