n,m=map(int,input().split())
MOD = 1000000007 
D=[0] * (n+2)
D[0] = 1
for _ in range(m):
    D[int(input())] = -1
for i in range(n):
    if D[i] == -1:
        continue
    if D[i+1] != -1:
        D[i+1] += D[i]
    if D[i+2] != -1:
        D[i+2] += D[i]
    D[i]%=MOD
print(D[n])