mod = 998244353

N = int(input())
S = input()
dp = [[0 for _ in range(N + 1)] for n in range(N + 1)]
dp[0][0] = 1
for n in range(N):
  if S[n] == '0':
    s = 0
    for m in range(n + 1):
      s = (s + dp[n][m]) % mod
      dp[n + 1][m + 1] = (m * dp[n][m] % mod + s) % mod
  else:
    for m in range(n + 1):
      dp[n + 1][m] = (n + 1 - m) * dp[n][m] % mod
ans = sum(dp[N]) % mod
print(ans)