N,M =map(int,input().split())
a = [int(input()) for i in range(M)]
DP = [1]*N
mod = 10**9 + 7
for i in a:
    DP[i-1] = 0
for i in range(N):
    if(DP[i] != 0):
        if(i<1):
            DP[i+1] = DP[i]%mod
        else:
            DP[i] = (DP[i-2]%mod + DP[i-1]%mod)
print(DP[-1])