#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;

#define REP(i,n) for(long long i = 0; i < (n); i++)
#define FOR(i, m, n) for(long long i = (m);i < (n); ++i)
#define ALL(obj) (obj).begin(),(obj).end()
#define SPEED cin.tie(0);ios::sync_with_stdio(false);

template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;
template<class T> using PQ = priority_queue<T>;
template<class T> using PQR = priority_queue<T,vector<T>,greater<T>>;

constexpr long long MOD = (long long)1e9 + 7;
constexpr long long MOD2 = 998244353;
constexpr long long HIGHINF = (long long)1e18;
constexpr long long LOWINF = (long long)1e15;
constexpr long double PI = 3.1415926535897932384626433;

template <class T> vector<T> multivector(size_t N,T init){return vector<T>(N,init);}
template <class... T> auto multivector(size_t N,T... t){return vector<decltype(multivector(t...))>(N,multivector(t...));}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; exit(0);}}
template <class T, class U>ostream &operator<<(ostream &o, const map<T, U>&obj) {o << "{"; for (auto &x : obj) o << " {" << x.first << " : " << x.second << "}" << ","; o << " }"; return o;}
template <class T>ostream &operator<<(ostream &o, const set<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const multiset<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const vector<T>&obj) {o << "{"; for (int i = 0; i < (int)obj.size(); ++i)o << (i > 0 ? ", " : "") << obj[i]; o << "}"; return o;}
template <class T, class U>ostream &operator<<(ostream &o, const pair<T, U>&obj) {o << "{" << obj.first << ", " << obj.second << "}"; return o;}
template <template <class tmp>  class T, class U> ostream &operator<<(ostream &o, const T<U> &obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr)o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
void print(void) {cout << endl;}
template <class Head> void print(Head&& head) {cout << head;print();}
template <class Head, class... Tail> void print(Head&& head, Tail&&... tail) {cout << head << " ";print(forward<Tail>(tail)...);}
template <class T> inline void chmax(T& a, const T b){a=max(a,b);}
template <class T> inline void chmin(T& a, const T b){a=min(a,b);}
void YN(bool flg) {cout << (flg ? "YES" : "NO") << endl;}
void Yn(bool flg) {cout << (flg ? "Yes" : "No") << endl;}
void yn(bool flg) {cout << (flg ? "yes" : "no") << endl;}

int main() {
	int N; cin >> N;
	string S; cin >> S;
	ll M=N,r=0,g=0,b=0,rg=0,gb=0,br=0,ans = 1;
	for(int i = 0; i < 3*N; ++i){
		if(S[i]=='R'){
			if(gb){
				(ans *= gb) %= MOD2;
				gb--;
			}
			else if(b){
				(ans *= b) %= MOD2;
				b--;
				br++;
			}
			else if(g){
				(ans *= g) %= MOD2;
				g--;
				rg++;
			}
			else{
				(ans *= M) %= MOD2;
				M--;
				r++;
			}
		}
		if(S[i]=='G'){
			if(br){
				(ans *= br) %= MOD2;
				br--;
			}
			else if(r){
				(ans *= r) %= MOD2;
				r--;
				rg++;
			}
			else if(b){
				(ans *= b) %= MOD2;
				b--;
				gb++;
			}
			else{
				(ans *= M) %= MOD2;
				M--;
				g++;
			}
		}
		if(S[i]=='B'){
			if(rg){
				(ans *= rg) %= MOD2;
				rg--;
			}
			else if(r){
				(ans *= r) %= MOD2;
				r--;
				br++;
			}
			else if(g){
				(ans *= g) %= MOD2;
				g--;
				gb++;
			}
			else{
				(ans *= M) %= MOD2;
				M--;
				b++;
			}
		}
	}
	cout << ans << endl;
}


Measured memory_bytes: 900