m = int(input())
a = list(map(int,input().split()))

N = 1000010
mod = 1000000007
fac = [1] * N
finv = [1] * N
inv = [1] * N

for i in range(2, N):
	fac[i] = fac[i - 1] * i % mod
	inv[i] = mod - inv[mod % i] * (mod // i) % mod
	finv[i] = finv[i - 1] * inv[i] % mod

def com(n, k):
	if n < k:
		return 0
	if n < 0 or k < 0:
		return 0
	return fac[n]*(finv[k]*finv[n - k]%mod) %mod

def calc(n, k):
	return com(n + k - 1, n)
s = 0
if a[0] != 0:
	s = len(a)

ans = calc(m - (sum(a) + s - 1), s + 1)
if ans == 0:
	print("NA")
else:
	print(ans)