n = int(input())
S = list(map(int,input()))
mod = 998244353

dp = [1,0]

for s in S:
    ndp = [0,0]
    if s:
        ndp[1] = (dp[1]*2 + dp[0]) % mod
    else:
        ndp[0] = (dp[0] + dp[1]) % mod
        ndp[1] = dp[1]
    dp = ndp

print(dp[1])