#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

#define rd_init() char*rp=({char*mmap();mmap(0l,1l<<25,1,2,0,0ll);})
#define rd_skip() while(*rp++>=48)
#define rd() ({long _v=0,_c;while(_c=*rp++-48,_c>=0)_v=_v*10+_c;_v;})
#define wt(v) ({ulong _z=v;do*--wp=_z%10+48;while(_z/=10);})
#define wt1(v) ({char wbuf[64],*wp=wbuf+sizeof wbuf;wt(v);write(1,wp,wbuf+sizeof wbuf-wp);})
#define rrep3(v,s,e) for(typeof(e) v=e;--v>=s;)
#define min(a,b) (a<=b?a:b)
#define MD 998244353

typedef unsigned long ulong;

//--------
// ifac table

#define M 300001
#define ifac_Mm1 988693096
unsigned ifac[M];

void mkfac(){
	ulong x=ifac_Mm1;
	for(long i=M;i--;){
		ifac[i]=x;
		x=x*i%MD;
	}
}

//--------

int inverse(int a){
	int b=MD;
	int u=1;
	int v=0;
	int s,t;
	while(b){
		t=a/b;
		s=b; b=a-t*b; a=s;
		s=v; v=u-t*v; u=s;
	}
	if(u<0){
		u+=MD;
	}
	return u;
}

int main(){
	int k,d;
	{
		rd_init();
		rd_skip();
		k=rd();
		d=0;
		for(int a,b=0;a=*rp++,a!=10;b=a){
			if(a=='N'){
				k-=1;
				d+=b!='C';
			}
		}
	}
	mkfac();
	{
		ulong z=0;
		rrep3(i,1,min(-k,d)+1){
			z=(z+(ulong)ifac[i]*ifac[d-i])%MD;
		}
		z=z*inverse(ifac[d])%MD;
		wt1(z);
	}
	_exit(0);
}