#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC push_options
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#include<bits/stdc++.h>
#include <xmmintrin.h>
#include <immintrin.h>
using namespace::std;
__attribute__((constructor))void init(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/priority_queue.hpp>
#include<ext/pb_ds/tag_and_trait.hpp>
// #include <boost/multiprecision/cpp_dec_float.hpp>
// #include <boost/multiprecision/cpp_int.hpp>
// namespace mp = boost::multiprecision;
// typedef mp::number<mp::cpp_dec_float<0>> cdouble;
// typedef mp::cpp_int cint;
template<typename T>using pbds=__gnu_pbds::tree<T,__gnu_pbds::null_type,less<T>,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<typename T>using pbds_map=__gnu_pbds::tree<T,T,less<T>,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<typename T,typename E>using hash_map=__gnu_pbds::gp_hash_table<T,E>;
template<typename T>using pqueue =__gnu_pbds::priority_queue<T, greater<T>,__gnu_pbds::rc_binomial_heap_tag>;
typedef long long lint;
#define INF (1LL<<60)
#define IINF (1<<30)
#define LINF (9223372036854775807LL)
#define EPS (1e-10)
#define endl ('\n')
//#define MOD 1000000007LL
#define MOD 998244353LL
//#define MOD 18446744069414584321ULL
typedef vector<lint> vec;
typedef vector<vector<lint>> mat;
typedef vector<vector<vector<lint>>> mat3;
typedef vector<string> svec;
typedef vector<vector<string>> smat;
template<typename T>inline void numout(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i<INF/2?i:"INF";f=1;}cout<<endl;}
template<typename T>inline void numout2(T t){for(auto i:t)numout(i);}
template<typename T>inline void output(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i;f=1;}cout<<endl;}
template<typename T>inline void output2(T t){for(auto i:t)output(i);}
template<typename T>inline void _output(T t){bool f=0;for(lint i=0;i<t.size();i++){cout<<f?"":" "<<t[i];f=1;}cout<<endl;}
template<typename T>inline void _output2(T t){for(lint i=0;i<t.size();i++)output(t[i]);}
#define rep(i,...) for(auto i:range(__VA_ARGS__)) 
#define rrep(i,...) for(auto i:reversed(range(__VA_ARGS__)))
#define repi(i,a,b) for(lint i=lint(a);i<(lint)(b);++i)
#define rrepi(i,a,b) for(lint i=lint(b)-1;i>=lint(a);--i)
#define irep(i) for(lint i=0;;++i)
inline vector<int64_t> range(int64_t n){vector<int64_t>v(n);iota(v.begin(),v.end(),0LL);return v;}
inline vector<int64_t> range(int64_t a,int64_t b){vector<int64_t>v(b-a);iota(v.begin(),v.end(),a);return v;}
inline vector<int64_t> range(int64_t a,int64_t b,int64_t c){vector<int64_t>v((b-a+c-1)/c);for(int i=0;i<(int)v.size();++i)v[i]=i?v[i-1]+c:a;return v;}
inline auto reversed(auto v){reverse(v.begin(),v.end());return v;}
#define all(n) begin(n),end(n)
#define dist(a,b,c,d) sqrt(pow(a-c,2)+pow(b-d,2))
//inline lint gcd(lint A,lint B){return B?gcd(B,A%B):A;}
//inline lint lcm(lint A,lint B){return A/gcd(A,B)*B;}
// inline cint cgcd(cint A,cint B){return B?cgcd(B,A%B):A;}
// inline cint clcm(cint A,cint B){return A/cgcd(A,B)*B;}
bool chmin(auto& s,const auto& t){bool res=s>t;s=min(s,t);return res;}
bool chmax(auto& s,const auto& t){bool res=s<t;s=max(s,t);return res;}
const vector<lint> dx={1,0,-1,0,1,1,-1,-1};
const vector<lint> dy={0,1,0,-1,1,-1,1,-1};
#define SUM(v) accumulate(all(v),0LL)
auto call=[](auto f,auto... args){return f(f,args...);};
template<typename T,typename ...Args>auto make_vector(T x,int arg,Args ...args){if constexpr(sizeof...(args)==0)return vector<T>(arg,x);else return vector(arg,make_vector<T>(x,args...));}

class mint {
  using u64 = std::uint_fast64_t;
    public:
    u64 a;
    constexpr mint(const long long x = 0)noexcept:a(x>=0?x%get_mod():get_mod()-(-x)%get_mod()){}
    constexpr u64 &value()noexcept{return a;}
    constexpr const u64 &value() const noexcept {return a;}
    constexpr mint operator+(const mint rhs)const noexcept{return mint(*this) += rhs;}
    constexpr mint operator-(const mint rhs)const noexcept{return mint(*this)-=rhs;}
    constexpr mint operator*(const mint rhs) const noexcept {return mint(*this) *= rhs;}
    constexpr mint operator/(const mint rhs) const noexcept {return mint(*this) /= rhs;}
    constexpr mint &operator+=(const mint rhs) noexcept {
        a += rhs.a;
        if (a >= get_mod())a -= get_mod();
        return *this;
    }
    constexpr mint &operator-=(const mint rhs) noexcept {
        if (a<rhs.a)a += get_mod();
        a -= rhs.a;
        return *this;
    }
    constexpr mint &operator*=(const mint rhs) noexcept {
        a = a * rhs.a % get_mod();
        return *this;
    }
    constexpr mint operator++(int n) noexcept {
        a += 1;
        if (a >= get_mod())a -= get_mod();
        return *this;
    }
    constexpr mint operator--(int n) noexcept {
        if (a<1)a += get_mod();
        a -= 1;
        return *this;
    }
    constexpr mint &operator/=(mint rhs) noexcept {
        u64 exp=get_mod()-2;
        while (exp) {
            if (exp % 2) {
                *this *= rhs;
            }
            rhs *= rhs;
            exp /= 2;
        }
        return *this;
    }
    constexpr bool operator==(mint x) noexcept {
        return a==x.a;
    }
    constexpr bool operator!=(mint x) noexcept {
        return a!=x.a;
    }
	constexpr bool operator<(mint x) noexcept {
        return a<x.a;
    }
	constexpr bool operator>(mint x) noexcept {
        return a>x.a;
    }
	constexpr bool operator<=(mint x) noexcept {
        return a<=x.a;
    }
	constexpr bool operator>=(mint x) noexcept {
        return a>=x.a;
    }
    constexpr static int root(){
        mint root = 2;
        while(root.pow((get_mod()-1)>>1).a==1)root++;
        return root.a;
    }
    constexpr mint pow(long long n){
        long long x=a;
        mint ret = 1;
        while(n>0) {
            if(n&1)(ret*=x);
            (x*=x)%=get_mod();
            n>>=1;
        }
        return ret;
    }
    constexpr mint inv(){
        return pow(get_mod()-2);
    }
    static vector<mint> fac,ifac;
    static bool init;
    constexpr static int mx=10000001;
    void build(){
        init=0;
        fac.resize(mx);
        ifac.resize(mx);
        fac[0]=1,ifac[0]=1;
        for(int i=1;i<mx;i++)fac[i]=fac[i-1]*i;
        ifac[mx-1]=fac[mx-1].inv();
        for(int i=mx-2;i>=0;i--)ifac[i]=ifac[i+1]*(i+1);
    }
    mint comb(lint b){
        if(init)build();
        if(a==0&&b==0)return 1;
        if((lint)a<b||a<0)return 0;
        return fac[a]*ifac[a-b]*ifac[b];
    }
    mint fact(){
        if(init)build();
        return fac[a];
    }
    mint fact_inv(){
        if(init)build();
        return ifac[a];
    }
    friend ostream& operator<<(ostream& lhs, const mint& rhs) noexcept {
        lhs << rhs.a;
        return lhs;
    }
    friend istream& operator>>(istream& lhs,mint& rhs) noexcept {
        lhs >> rhs.a;
        return lhs;
    }
    constexpr static u64 get_mod(){return MOD;}
};
vector<mint> mint::fac;
vector<mint> mint::ifac;
bool mint::init=1;

constexpr int N=20;
mint f(bitset<N>v,const string& s,lint n){
    mint ans=0;
    {
        for(int i=0;i<n-(int)s.size()+1;++i){
            bool b=1;
            rep(j,s.size()){
                if((s[j]=='-')^(v[i+j]))b=0;
            }
            if(b)ans+=mint(n).pow(n-v.count());
        }
    }
    if(int(v.count())==n)return ans;
    for(int i=0;i<n;++i){
        bitset<N>b=v;
        lint tmp=i;
        while(b[tmp++%n]);
        b[(tmp+n-1)%n]=1;
        ans+=f(b,s,n);
    }
    return ans;
}

int main(){
    lint n,m;
    cin>>n>>m;
    string s;
    cin>>s;
    //cout<<f(bitset<N>(),s,n)<<endl;
    auto f=[](lint n,lint k)->mint{
        n++;
        if(k==0)return 1;
        return mint(n-k)*mint(n).pow(k-1);
    };
    if(count(all(s),'o')==0){
        mint ans=0;
        rep(i,n-m+1){
            mint tmp=0;
            tmp+=mint(n).pow(i+m);
            if(n-m-i>=1){
                tmp-=mint(m)*f(n-1,i+m);
            }
            if(n-m-i>=2){
                for(int j=0;j<=m-2;++j){
                    tmp+=mint(m-1-j)*f(n-(j+2),i+m-j)*f(j,j)*mint(i+m).comb(j);
                }
            }
            ans+=tmp*(n-m+1)*mint(n).pow(n-m-i);
        }
        cout<<ans<<endl;
    }else{
        vec v;
        lint now=0;
        rep(i,m){
            if(s[i]=='o'){
                if(now)v.push_back(now);
                now=0;
            }else{
                now++;
            }
        }
        lint l=(s[0]=='o'?0:v[0]),r=now;
        if(s[0]!='o')v.erase(v.begin());
        mint tmp=1;
        lint cnt=0;
        for(auto e:v){
            tmp*=f(e,e);
            tmp/=mint(e).fact();
            cnt+=e;
        }
        tmp*=mint(cnt).fact();
        mint ans=0;
        vector<mint>table(max(l+r-1,1LL),0);
        rep(i,l)rep(j,r){
            table[i+j]+=f(i,i)*f(j,j)*mint(i+j).comb(i);
        }
        rep(i,n-m+1){
            mint tmp2=0;
            tmp2+=f(n-m+l+r,i+l+r);
            if(n-m-i>=1){
                for(int j=0;j<=l-1;++j){
                    tmp2-=f((n-m+l+r)-(1+j),(i+l+r)-j)*f(j,j)*mint(i+l+r).comb(j);
                }
                for(int j=0;j<=r-1;++j){
                    tmp2-=f((n-m+l+r)-(1+j),(i+l+r)-j)*f(j,j)*mint(i+l+r).comb(j);
                }
            }
            if(n-m-i>=2){
                for(int j=0;j<=l+r-2;++j){
                    tmp2+=f((n-m+l+r)-(2+j),(i+l+r)-j)*table[j]*mint(i+l+r).comb(j);
                }
            }
            ans+=tmp*tmp2*mint(i+l+r+cnt).comb(cnt)*(n-m+1)*mint(n).pow(n-i-cnt-l-r);
        }
        cout<<ans<<endl;
    }
}