n,m = list(map(int,input().split()))
a = [0]*m
for i in range(m):
    a[i] = int(input())
memo = [-1]*(n+1)

def stair(k):
    if memo[k] != -1:
        return memo[k]
    else:
        if k == 1:
            if 1 not in a:
                memo[k] = 1
            else:
                memo[k] = 0
        elif k == 2:
            if 2 not in a:
                memo[k] = 1 + stair(1)
            else:
                memo[k] = 0 + stair(1)
        elif k not in a:
            if k-1 not in a:
                if k-2 not in a:
                    memo[k] = (stair(k-1)+stair(k-2))%1000000007
                else:
                    memo[k] = stair(k-1)
            else:
                if k-2 not in a:
                    memo[k] = stair(k-2)
                else:
                    memo[k] = 0
        else:
            memo[k] = 0
    return memo[k]

print(stair(n))