N = int(input())
A = input()
MOD = 998244353

dp = [1,0,0]

for char in A:
	next_dp = [0,0,0]
	
	if char == '0':
		next_dp[0] = (dp[0]) % MOD
		next_dp[1] = (dp[1]) % MOD
		next_dp[2] = (dp[0] + dp[1] + dp[2]) % MOD
	else:
		next_dp[1] = (dp[0] + dp[1]) % MOD
		next_dp[2] = (dp[2]) % MOD
	dp = next_dp
	
print(sum(dp) % MOD)