MOD = 10**9 + 7
max_n = 2 * 10**6 + 5  # Precompute up to 2 million + 5 to handle large cases

# Precompute factorial and inverse factorial modulo MOD
fact = [1] * (max_n + 1)
for i in range(1, max_n + 1):
    fact[i] = fact[i-1] * i % MOD

inv_fact = [1] * (max_n + 1)
inv_fact[max_n] = pow(fact[max_n], MOD - 2, MOD)
for i in range(max_n - 1, -1, -1):
    inv_fact[i] = inv_fact[i + 1] * (i + 1) % MOD

def solve():
    M = int(input())
    H = list(map(int, input().split()))
    k = len(H)
    if k == 0:
        print("NA")
        return
    if k == 1:
        if H[0] == 0:
            print(1)
            return
    # Check if any element is zero in case of k > 1
    valid = True
    if k > 1:
        for h in H:
            if h <= 0:
                valid = False
                break
    if not valid:
        print("NA")
        return
    sum_h = sum(H)
    required = sum_h + (k - 1)
    if required > M:
        print("NA")
        return
    rem = M - required
    n = rem + k
    if k > n:
        print(0)
        return
    if n > max_n:
        print("NA")
        return
    res = fact[n] * inv_fact[k] % MOD
    res = res * inv_fact[n - k] % MOD
    print(res)

solve()