MOD = 10 ** 9 + 7

M = int(input())
N = M + 1
fact = [1]*(N+1)
rfact = [1]*(N+1)
r = 1
for i in range(1, N+1):
    fact[i] = r = r * i % MOD
rfact[N] = r = pow(fact[N], -1, MOD)
for i in range(N, 0, -1):
    rfact[i-1] = r = r * i % MOD

# nCk (mod MOD) を求める
def comb(n, k):
    return fact[n] * rfact[k] * rfact[n-k] % MOD

H = list(map(int,input().split()))
K = len(H)
sumh = sum(H)
if sumh == 0:
    K = 0
if sumh + K -1 > M:
    print("NA")
    exit()
print(comb(M - sumh + 1,K))