#include <bits/stdc++.h>
#define x first
#define y second
using namespace std;
using ll=long long;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using vi=vector<int>;
using vl=vector<ll>;
#define pb push_back
#define all(a) begin(a),end(a)

const int N=300010;
const char en='\n';
const ll LLINF=1ll<<60,MOD=998244353,root=62;

ll mul(ll a,ll b)
{
	return a*b%MOD;
}

ll pot(ll n,ll k)
{
	if (k==0) return 1;
	ll x=pot(n,k/2);
	x=mul(x,x);
	if (k%2) x=mul(x,n);
	return x;
}

void ntt(vl&a)
{
	int n=a.size(),L=31-__builtin_clz(n);
	static vl rt(2,1);
	for (static int k=2,s=2;k<n;k*=2,s++)
	{
		rt.resize(n);
		ll z[]={1,pot(root,MOD>>s)};
		for (int i=k;i<2*k;++i) rt[i]=(rt[i/2]*z[i&1])%MOD;
	}
	vi rev(n);
	for (int i=0;i<n;++i) rev[i]=(rev[i/2]|(i&1)<<L)/2;
	for (int i=0;i<n;++i) if (i<rev[i]) swap(a[i],a[rev[i]]);
	for (int k=1;k<n;k*=2) for (int i=0;i<n;i+=2*k) for (int j=0;j<k;++j)
	{
		ll z=(rt[j+k]*a[i+j+k])%MOD,&ai=a[i+j];
		a[i+j+k]=ai-z+(z>ai?MOD:0);
		ai+=(ai+z>=MOD?z-MOD:z);
	}
}

vl conv(vl a,vl b)
{
	if (a.empty() || b.empty()) return {};
	int s=a.size()+b.size()-1,B=32-__builtin_clz(s),n=1<<B;
	if (min(a.size(),b.size())<10)
	{
		vl c(s);
		for (int i=0;i<(int)a.size();++i) for (int j=0;j<(int)b.size();++j) c[i+j]+=a[i]*b[j];
		for (int i=0;i<(int)c.size();++i) c[i]%=MOD;
		return c;
	}
	int inv=pot(n,MOD-2);
	vl L(a),R(b),out(n);
	L.resize(n),R.resize(n);
	ntt(L),ntt(R);
	for (int i=0;i<n;++i) out[-i&(n-1)]=(((L[i]*R[i])%MOD)*inv)%MOD;
	ntt(out);
	return {out.begin(),out.begin()+s};
}

vl padd(vl a,vl b)
{
	if (b.size()<a.size()) swap(a,b);
	while (a.size()<b.size()) a.pb(0);
	for (int i=0;i<(int)a.size();++i)
	{
		a[i]+=b[i];
		if (a[i]>=MOD) a[i]-=MOD;
	}
	return a;
}

using mat=array<array<vl,2>,2>;

mat mmul(mat a,mat b)
{
	mat c;
	for (int i=0;i<2;++i) for (int j=0;j<2;++j)
	{
		//cout<<"M"<<i<<' '<<j<<endl;
		c[i][j]={};
		for (int k=0;k<2;++k) c[i][j]=padd(c[i][j],conv(a[i][k],b[k][j]));
	}
	//cout<<"KR"<<endl;
	return c;
}

int n;
string h;

mat dq(int l,int r)
{
	//cout<<l<<' '<<r<<endl;
	if (r-l==2)
	{
		mat c;
		for (int i=0;i<2;++i) if ((h[l]!='B' && i==0) || (h[l]!='R' && i==1))
		{
			for (int j=0;j<2;++j) if ((h[r]!='B' && j==0) || (h[r]!='R' && j==1))
			{
				if (i==j)
				{
					c[i][j]={0,1+(h[l+1]=='?')};
				}
				else if (i==0)
				{
					c[i][j]={0,(h[l+1]=='?' || h[l+1]=='P'),(h[l+1]=='?' || h[l+1]=='Y')};
				}
				else
				{
					c[i][j]={(h[l+1]=='?' || h[l+1]=='Y'),(h[l+1]=='?' || h[l+1]=='P')};
				}
			}
		}
		return c;
	}
	int mid=(l+r)/2;
	if (mid%2) --mid;
	return mmul(dq(l,mid),dq(mid,r));
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin>>n>>h;
	string h1;
	h1.pb(h.back());
	h1+=h;
	h=h1;
	mat x=dq(0,2*n);
	/*for (auto y: x[0][0]) cout<<y<<' ';
	cout<<en;
	for (auto y: x[0][1]) cout<<y<<' ';
	cout<<en;
	for (auto y: x[1][0]) cout<<y<<' ';
	cout<<en;
	for (auto y: x[1][1]) cout<<y<<' ';
	cout<<endl;*/
	int an=0;
	if ((int)x[0][0].size()>n) an=(an+x[0][0][n])%MOD;
	if ((int)x[1][1].size()>n) an=(an+x[1][1][n])%MOD;
	cout<<an<<en;
}