N = int(input())
S = input()

MOD = 998244353
dp = [[0]*2 for _ in range(N+1)]
dp[0][0] = 1
for i in range(N):
    if S[i] == "0":
        dp[i+1][0] += dp[i][0]
        dp[i+1][0] %= MOD
        dp[i+1][1] += dp[i][1]
        dp[i+1][1] %= MOD
        dp[i+1][0] += dp[i][1]
        dp[i+1][0] %= MOD
    else:
        dp[i+1][1] += dp[i][0]
        dp[i+1][1] %= MOD
        dp[i+1][1] += dp[i][1]*2
        dp[i+1][1] %= MOD

print(dp[-1][1])