import sys
input = sys.stdin.readline

N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
dp = [0] * N
broke = False
if 1 in a and 2 not in a:
    dp[1] = 1
elif 1 not in a and 2 in a:
    dp[0] = 1
else:
    dp[0] = 1
    dp[1] = 2
if 1 in a and 2 in a:
    print('0')
    broke = True
else:
    for i in range(3,N+1):
        if i-1 in a and i-2 in a:
            print('0')
            broke = True
            break
        elif i-1 in a:
            dp[i-1] = dp[i-3]
        elif i-2 in a:
            dp[i-1] = dp[i-2]
        else:
            dp[i-1] = (dp[i-2] + dp[i-3]) % 1000000007
if broke == False:
    print(dp[N-1])