MOD = 998244353

N = int(input())
A = input().strip()

prefix_zero = [False] * (N + 1)
suffix_one = [False] * (N + 2)

for i in range(1, N + 1):
    prefix_zero[i] = prefix_zero[i - 1] or (A[i - 1] == '0')

for i in range(N, 0, -1):
    suffix_one[i] = suffix_one[i + 1] or (A[i - 1] == '1')

ans = 0

for k in range(0, N + 1):
    ok_left = (k == 0) or prefix_zero[k]
    ok_right = (k == N) or suffix_one[k + 1]

    if ok_left and ok_right:
        ans += 1

print(ans % MOD)