import sys
n,m=map(int,input().split())
if m==0:
    x=1
    y=2
    for i in range(n-2):
        if x<y:
            x+=y%1000000007
        else:
            y+=x%1000000007
    print(max(x,y)%1000000007)
    sys.exit()
a=list(int(input()) for i in range (m))

x=['']*n
if a[0]==1:
    x[0]=0
else:
    x[0]=1

if m>=2:
	if a[0]!=2 and a[1]!=2:
		x[1]=x[0]+1
    

else:
    if a[0]!=2:
	       x[1]=x[0]+1
    elif a[0]==2:
        x[1]=0


for z in range(m):
    x[a[z]-1]=0
        
if n>=4:
    for k in range(2,n):
        if x[k]!=0:
            x[k]=x[k-2]%1000000007+x[k-1]%1000000007
            
elif n==1:
    print(1)
    sys.exit()
    
elif n==2:
    print(x[0]+1)
    sys.exit()
    
print(x[n-1]%1000000007)