#include using namespace std; typedef long long ll; typedef pair p_ll; template void debug(T itr1, T itr2) { auto now = itr1; while(now=0; i--) const ll LLINF = pow(2,61)-1; const int INF = pow(2,30)-1; const ll MOD = 998244353; vector fac; void c_fac(ll x=pow(10,7)+10) { fac.resize(x); rep(i,x) fac[i] = i ? fac[i-1]*i%MOD : 1; } vector> nck; void c_nck(ll N) { nck.resize(N+1, vector(N+1)); nck[0][0] = 1; rep(i,N+1) rep(j,N+1) { if (i) nck[i][j] = (nck[i][j] + nck[i-1][j]) % MOD; if (i&&j) nck[i][j] = (nck[i][j] + nck[i-1][j-1]) % MOD; } } int main() { ll N; cin >> N; string S; cin >> S; ll c0 = 0, c1 = 0; rep(i,N) { if (S[i]=='0') c0++; else c1++; } c_fac(N+1); c_nck(N); assert(1<=N && N<=5000); rep(i,N) assert(S[i]=='0'||S[i]=='1'); vector> dp(N+1, vector(N+1)); dp[0][0] = 1; rep(i,N) rep(j,N+1) { if (i+2<=N&&j+1<=N) dp[i+2][j+1] = (dp[i+2][j+1] + dp[i][j]*(i+1)) % MOD; if (j+1<=N) dp[i+1][j+1] = (dp[i+1][j+1] + dp[i][j]*(i-j)) % MOD; dp[i+1][j] = (dp[i+1][j] + dp[i][j]*j) % MOD; } // rep(i,N+1) debug(all(dp[i])); ll result = 0; rep(eq01,N+1) { ll select_eq = nck[c0+c1][eq01] * fac[eq01] % MOD; rep(eq0,eq01+1) { ll eq1 = eq01 - eq0; if (eq0>c0||eq1>c1) continue; ll select_01 = (nck[c0][eq0] * fac[c0-eq0] % MOD) * (nck[c1][eq1] * fac[c1-eq1] % MOD) % MOD; result = (result + select_eq * select_01 % MOD * dp[N-eq01][c0-eq0] % MOD) % MOD; // cout << eq0 << " " << eq1 << "->" << select_eq * select_01 % MOD * dp[N-eq01][c0-eq0] % MOD << endl; } } cout << result << endl; return 0; }