#include <bits/stdc++.h>
using namespace std;
const int mod = 998244353;
int dp[2][506][1015][2];

void mk(int &a, int b) {
	(a += b);
	a -= (a >= mod ? mod : 0);
}

signed main() {
	int n;
	string s;
	cin >> n >> s;
	s = ' ' + s;
	dp[(n + 1) & 1][0][505][0] = 1;
	for (int i = n; i; i--) {
		memset(dp[i & 1], 0, sizeof(dp[i & 1]));
		if (s[i] != '0')
			for (int j = 0; j <= ((n - i + 1) + 2) / 3; j++)
				for (int k = 506 - (n - i + 1); k <= 505 + j; k++)
					if (k - 502 <= j + 1)
						mk(dp[i & 1][max(j, k - 502)][k + 3][1], dp[i & 1 ^ 1][j][k][0]);
		if (s[i] != '1')
			for (int j = 0; j <= ((n - i + 1) + 2) / 3; j++)
				for (int k = 506 - (n - i + 1); k <= 505 + j; k++)
					for (int tp : {
					            0, 1
					        })
						mk(dp[i & 1][j][k - 1][0], dp[i & 1 ^ 1][j][k][tp]);
	}
	int ans = 0;
	for (int i = 0; i <= 505; i++) {
		ans += dp[1][i][505][0];
	}
	cout << ans << '\n';
	return 0;
}