#include <bits/stdc++.h>   using namespace std;   long long w[2], b[2], q[2], mod = 998244353, fac[100001];   long long modpow(long long b, long long p) {     long long ret = 1;     while (p > 0) {       if (p & 1) ret = ret * b % mod;       b = b * b % mod;       p >>= 1;     }     return ret;   }   long long choose(long long n, long long m) {     long long denom = modpow(fac[m], mod - 2) * modpow(fac[n - m], mod - 2) % mod;     return (fac[n] * denom % mod);   }   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     long long n, qq = 0;     bool bw = true, wb = true, both = true;     string s;     fac[0] = 1;     for (int i = 1; i < 100001; i++) fac[i] = fac[i - 1] * i % mod;     cin >> n;     for (int i = 0; i < n; i++) {       cin >> s;       for (int j = 0; j < 2; j++) {         if (s[j] ==  W ) w[j]++;         if (s[j] ==  B ) b[j]++;         if (s[j] ==  ? ) q[j]++;       }       if (s ==  ?? ) qq++;       if (s ==  WW  || s ==  BB ) bw = wb = both = false;       if (s ==  W?  || s ==  ?B  || s ==  WB ) bw = false;       if (s ==  B?  || s ==  ?W  || s ==  BW ) wb = false;     }     if (n == 1) {       if (s ==  WW  | s ==  BB )         cout << 0;       else if (s ==  ?? )         cout << 2;       else         cout << 1;       return 0;     }     long long ans = 0;     for (int i = 0; i < q[0] + 1; i++) {       if (w[0] + i < b[1] || w[0] + i > b[1] + q[1]) continue;       ans = (ans + choose(q[0], i) * choose(q[1], w[0] + i - b[1])) % mod;     }     if (both) {       ans -= modpow(2, qq);       if (bw) ans++;       if (wb) ans++;     }     ans = ((ans % mod) + mod) % mod;     cout << ans;   }   