#pragma GCC optimize ("Ofast")
#include<bits/stdc++.h>
using namespace std;
struct mint{
  static unsigned R, RR, Rinv, W, md, mdninv;
  unsigned val;
  mint(){
  }
  mint(int a){
    val = mulR(a);
  }
  mint(unsigned a){
    val = mulR(a);
  }
  mint(long long a){
    val = mulR(a);
  }
  mint(unsigned long long a){
    val = mulR(a);
  }
  int get_inv(long long a, int md){
    long long e, s=md, t=a, u=1, v=0;
    while(s){
      e=t/s;
      t-=e*s;
      u-=e*v;
      swap(t,s);
      swap(u,v);
    }
    if(u<0){
      u+=md;
    }
    return u;
  }
  void setmod(unsigned m){
    int i;
    unsigned t;
    W = 32;
    md = m;
    R = (1ULL << W) % md;
    RR = (unsigned long long)R*R % md;
    switch(m){
      case 104857601:
      Rinv = 2560000;
      mdninv = 104857599;
      break;
      case 998244353:
      Rinv = 232013824;
      mdninv = 998244351;
      break;
      case 1000000007:
      Rinv = 518424770;
      mdninv = 2226617417U;
      break;
      case 1000000009:
      Rinv = 171601999;
      mdninv = 737024967;
      break;
      case 1004535809:
      Rinv = 234947584;
      mdninv = 1004535807;
      break;
      case 1007681537:
      Rinv = 236421376;
      mdninv = 1007681535;
      break;
      case 1012924417:
      Rinv = 238887936;
      mdninv = 1012924415;
      break;
      case 1045430273:
      Rinv = 254466304;
      mdninv = 1045430271;
      break;
      case 1051721729:
      Rinv = 257538304;
      mdninv = 1051721727;
      break;
      default:
      Rinv = get_inv(R, md);
      mdninv = 0;
      t = 0;
      for(i=0;i<((int)W);i++){
        if(t%2==0){
          t+=md;
          mdninv |= (1U<<i);
        }
        t /= 2;
      }
    }
  }
  unsigned mulR(unsigned a){
    return (unsigned long long)a*R%md;
  }
  unsigned mulR(int a){
    if(a < 0){
      a = a%((int)md)+(int)md;
    }
    return mulR((unsigned)a);
  }
  unsigned mulR(unsigned long long a){
    return mulR((unsigned)(a%md));
  }
  unsigned mulR(long long a){
    a %= md;
    if(a < 0){
      a += md;
    }
    return mulR((unsigned)a);
  }
  unsigned reduce(unsigned T){
    unsigned m=T * mdninv, t=(unsigned)((T + (unsigned long long)m*md) >> W);
    if(t >= md){
      t -= md;
    }
    return t;
  }
  unsigned reduce(unsigned long long T){
    unsigned m=(unsigned)T * mdninv, t=(unsigned)((T + (unsigned long long)m*md) >> W);
    if(t >= md){
      t -= md;
    }
    return t;
  }
  unsigned get(){
    return reduce(val);
  }
  mint &operator+=(mint a){
    val += a.val;
    if(val >= md){
      val -= md;
    }
    return *this;
  }
  mint &operator-=(mint a){
    if(val < a.val){
      val = val + md - a.val;
    }
    else{
      val -= a.val;
    }
    return *this;
  }
  mint &operator*=(mint a){
    val = reduce((unsigned long long)val*a.val);
    return *this;
  }
  mint &operator/=(mint a){
    return *this *= a.inverse();
  }
  mint operator+(mint a){
    return mint(*this)+=a;
  }
  mint operator-(mint a){
    return mint(*this)-=a;
  }
  mint operator*(mint a){
    return mint(*this)*=a;
  }
  mint operator/(mint a){
    return mint(*this)/=a;
  }
  mint operator+(int a){
    return mint(*this)+=mint(a);
  }
  mint operator-(int a){
    return mint(*this)-=mint(a);
  }
  mint operator*(int a){
    return mint(*this)*=mint(a);
  }
  mint operator/(int a){
    return mint(*this)/=mint(a);
  }
  mint operator+(long long a){
    return mint(*this)+=mint(a);
  }
  mint operator-(long long a){
    return mint(*this)-=mint(a);
  }
  mint operator*(long long a){
    return mint(*this)*=mint(a);
  }
  mint operator/(long long a){
    return mint(*this)/=mint(a);
  }
  mint operator-(void){
    mint res;
    if(val){
      res.val=md-val;
    }
    else{
      res.val=0;
    }
    return res;
  }
  operator bool(void){
    return val!=0;
  }
  operator int(void){
    return get();
  }
  operator long long(void){
    return get();
  }
  mint inverse(){
    int a=val, b=md, t, u=1, v=0;
    mint res;
    while(b){
      t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    if(u < 0){
      u += md;
    }
    res.val = (unsigned long long)u*RR % md;
    return res;
  }
  mint pw(unsigned long long b){
    mint a(*this), res;
    res.val = R;
    while(b){
      if(b&1){
        res *= a;
      }
      b >>= 1;
      a *= a;
    }
    return res;
  }
  bool operator==(int a){
    return mulR(a)==val;
  }
  bool operator!=(int a){
    return mulR(a)!=val;
  }
}
;
mint operator+(int a, mint b){
  return mint(a)+=b;
}
mint operator-(int a, mint b){
  return mint(a)-=b;
}
mint operator*(int a, mint b){
  return mint(a)*=b;
}
mint operator/(int a, mint b){
  return mint(a)/=b;
}
mint operator+(long long a, mint b){
  return mint(a)+=b;
}
mint operator-(long long a, mint b){
  return mint(a)-=b;
}
mint operator*(long long a, mint b){
  return mint(a)*=b;
}
mint operator/(long long a, mint b){
  return mint(a)/=b;
}
inline void rd(int &x){
  int k, m=0;
  x=0;
  for(;;){
    k = getchar_unlocked();
    if(k=='-'){
      m=1;
      break;
    }
    if('0'<=k&&k<='9'){
      x=k-'0';
      break;
    }
  }
  for(;;){
    k = getchar_unlocked();
    if(k<'0'||k>'9'){
      break;
    }
    x=x*10+k-'0';
  }
  if(m){
    x=-x;
  }
}
inline void rd(char &c){
  int i;
  for(;;){
    i = getchar_unlocked();
    if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF){
      break;
    }
  }
  c = i;
}
inline int rd(char c[]){
  int i, sz=0;
  for(;;){
    i = getchar_unlocked();
    if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF){
      break;
    }
  }
  c[sz++] = i;
  for(;;){
    i = getchar_unlocked();
    if(i==' '||i=='\n'||i=='\r'||i=='\t'||i==EOF){
      break;
    }
    c[sz++] = i;
  }
  c[sz]='\0';
  return sz;
}
inline void wt_L(char a){
  putchar_unlocked(a);
}
inline void wt_L(int x){
  char f[10];
  int m=0, s=0;
  if(x<0){
    m=1;
    x=-x;
  }
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  if(m){
    putchar_unlocked('-');
  }
  while(s--){
    putchar_unlocked(f[s]+'0');
  }
}
inline void wt_L(mint x){
  int i;
  i = (int)x;
  wt_L(i);
}
unsigned mint::R, mint::RR, mint::Rinv, mint::W, mint::md, mint::mdninv;
#define MD 998244353
int N;
char S[300001];
int Rs;
int Gs;
int Bs;
int up[100000];
int md[100000];
int dw[100000];
mint dp[100000];
mint s[100001];
mint nx[100000];
int main(){
  int i, j, k;
  mint res, tmp;
  {
    mint x;
    x.setmod(MD);
  }
  rd(N);
  rd(S);
  k = 0;
  for(i=0;i<(3*N);i++){
    if(S[i]=='R'){
      up[Rs++] = i;
    }
    if(S[i]=='G'){
      md[Gs++] = i;
    }
    if(S[i]=='B'){
      dw[Bs++] = i;
    }
    if(Rs > k && Gs > k && Bs > k){
      if(up[k] > md[k]){
        swap(up[k], md[k]);
      }
      if(md[k] > dw[k]){
        swap(md[k], dw[k]);
      }
      if(up[k] > md[k]){
        swap(up[k], md[k]);
      }
      ;
      k++;
    }
  }
  res = 1;
  j = N-1;
  for(i=N-1;i>=0;i--){
    while(j>=0 && dw[j] > md[i]){
      j--;
    }
    res *= i - j;
  }
  j = N-1;
  for(i=N-1;i>=0;i--){
    while(j>=0 && md[j] > up[i]){
      j--;
    }
    res *= i - j;
  }
  for(i=0;i<(N);i++){
    res *= i+1;
  }
  wt_L(res);
  wt_L('\n');
  return 0;
}
// cLay varsion 20190902-1

// --- original code ---
// #define MD 998244353
// 
// int N;
// char S[300001];
// 
// int Rs, Gs, Bs;
// int up[1d5], md[1d5], dw[1d5];
// 
// mint dp[1d5], s[100001], nx[1d5];
// 
// {
//   int i, j, k;
//   mint res, tmp;
//   
//   rd(N,S);
// 
//   k = 0;
//   rep(i,3N){
//     if(S[i]=='R') up[Rs++] = i;
//     if(S[i]=='G') md[Gs++] = i;
//     if(S[i]=='B') dw[Bs++] = i;
//     if(Rs > k && Gs > k && Bs > k){
//       sortE(up[k], md[k], dw[k]);
//       k++;
//     }
//   }
// 
//   res = 1;
// 
//   j = N-1;
//   for(i=N-1;i>=0;i--){
//     while(j>=0 && dw[j] > md[i]) j--;
//     res *= i - j;
//   }
// 
//   j = N-1;
//   for(i=N-1;i>=0;i--){
//     while(j>=0 && md[j] > up[i]) j--;
//     res *= i - j;
//   }
// 
//   rep(i,N) res *= i+1;
//   
//   wt(res);
// }


Measured memory_bytes: 1664