#dp
n,m  = map(int,input().split())
ln = [-1 for i in range(n +1)]
mod_1 = 10**9 + 7
for i in range(m):
    ln[int(input())] = 0
line = []
for i in range(n+1):
    if ln[i] ==0
        pass
    elif i == 0:
        ln[i] = 1
    elif i == 1:
        ln[i] = 1
    else:
        line.append((line[-1] + line[-2]) % mod_1)
print(line[-1])
