N,W = input().split()
aArr = list()
ans = 0
tmp = int(N)
for i in range(int(W)):
    inputInt = int(input())
    aArr.append(inputInt)
    if inputInt - tmp == 1:
        print(ans)
        exit()
    tmp = inputInt
tmp = 0
intArr = list()
for i in range(int(N)+1):
    if(i in aArr):
        intArr.append(0)
    elif i < 2:
        intArr.append(1)
    else:
        intArr.append(intArr[i-2] + intArr[i-1])
print(intArr[int(N)] % 1000000007)
