import sys
sys.setrecursionlimit(10**6)
readline = sys.stdin.readline

n,m = [int(i) for i in readline().split()]
a = [int(j) for j in range(m)]
dp = [1]*2 + [0]*(n-1)
mod = 1000000007
 
for i in range(1,m):
  if a[i]==a[i-1]+1:
    print(0)
    sys.exit()
  
for i in range(n-1):
  if i+1 in a:
    dp[i+2] = dp[i]
    dp[i+1] = 0
  else:
    dp[i+2] = dp[i]+dp[i+1]

print(dp[-1]%mod)  
