#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 #include #include using namespace::std; __attribute__((constructor))void init(){cin.tie(0);ios::sync_with_stdio(false);cout< #include #include #include // #include // #include // namespace mp = boost::multiprecision; // typedef mp::number> cdouble; // typedef mp::cpp_int cint; templateusing pbds=__gnu_pbds::tree,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>; templateusing pbds_map=__gnu_pbds::tree,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>; templateusing hash_map=__gnu_pbds::gp_hash_table; templateusing pqueue =__gnu_pbds::priority_queue,__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 vec; typedef vector> mat; typedef vector>> mat3; typedef vector svec; typedef vector> smat; templateinline void numout(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<inline void numout2(T t){for(auto i:t)numout(i);} templateinline void output(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<inline void output2(T t){for(auto i:t)output(i);} templateinline void _output(T t){bool f=0;for(lint i=0;iinline void _output2(T t){for(lint i=0;i=lint(a);--i) #define irep(i) for(lint i=0;;++i) inline vector range(int64_t n){vectorv(n);iota(v.begin(),v.end(),0LL);return v;} inline vector range(int64_t a,int64_t b){vectorv(b-a);iota(v.begin(),v.end(),a);return v;} inline vector range(int64_t a,int64_t b,int64_t c){vectorv((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 dx={1,0,-1,0,1,1,-1,-1}; const vector 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...);}; templateauto make_vector(T x,int arg,Args ...args){if constexpr(sizeof...(args)==0)return vector(arg,x);else return vector(arg,make_vector(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= 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(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 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=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>(istream& lhs,mint& rhs) noexcept { lhs >> rhs.a; return lhs; } constexpr static u64 get_mod(){return MOD;} }; vector mint::fac; vector mint::ifac; bool mint::init=1; int main(){ lint n,m; cin>>n>>m; string s; cin>>s; vec v; lint now=0; rep(i,m){ if(s[i]=='o'){ if(now)v.push_back(now); now=0; }else{ now++; } } auto f=[](lint n,lint k)->mint{ n++; if(k==0)return 1; return mint(n-k)*mint(n).pow(k-1); }; 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; rep(i,n-m+1){ ans+=f(n-m,i)*mint(i+cnt).comb(i)*(n-m+1)*mint(n).pow(n-i-cnt); } cout<