#C
import sys
sys.setrecursionlimit(1000000)
mod=10**9+7
n,m=map(int,input().split())
a=[int(input()) for i in range(m)]
def f(x):
    b=1
    c=1
    if x==1 or x==0:
        return 1
    else:
        for i in range(x-1):
            b,c=(b+c)%mod,b
        return b
s=f(a[0]-1)
for i in range(1,m):
    if a[i]-a[i-1]==1:
        print(0)
        break
    s=(s*f(a[i]-a[i-1]-2))%mod
else:
    s=(s*f(n-a[m-1]-1))%mod
    print(s)