#include #include using namespace std; using namespace atcoder; typedef long long int ll; typedef long double ld; typedef vector vi; typedef vector vvi; typedef vector vvvi; typedef vector vvvvi; typedef pair pi; typedef pair ppi; typedef pair pppi; typedef pair ppppi; #define FOR(i,l,r) for(ll i=l;i=l;i--) #define RREP(i,n) RFOR(i,0,n) #define ALL(x) x.begin(),x.end() #define F first #define S second #define BS(A,x) binary_search(ALL(A),x) #define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin()) #define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin()) #define COU(A,x) (UB(A,x)-LB(A,x)) #define sz(c) ((ll)(c).size()) /* #include namespace mp=boost::multiprecision; using Bint=mp::cpp_int; */ templateusing min_priority_queue=priority_queue,greater>; templateostream&operator<<(ostream&os,pair&p){os<istream&operator>>(istream&is,pair&p){is>>p.F>>p.S;return is;} templateostream&operator<<(ostream&os,vector&v){REP(i,sz(v))os<istream&operator>>(istream&is,vector&v){for(T&in:v)is>>in;return is;} templatebool chmax(T&a,T b){if(abool chmin(T&a,T b){if(b vm; typedef vector vvm; typedef vector vvvm; typedef vector vvvvm; ostream&operator<<(ostream&os,mint&a){os<>N>>M>>K>>S; vvm DP(M+1,vm(28)); DP[0][0]=1; REP(j,M)REP(k,27){ DP[j+1][k+1]+=DP[j][k]*(26-k); DP[j+1][k]+=DP[j][k]*k; } REP(i,M)REP(j,28)DP[i+1][j]+=DP[i][j]; vectorseen(26); ll cnt=0; mint ans=0; REP(i,N-1){ if(!seen[S[i]-'a']){seen[S[i]-'a']=1;cnt++;} if(cnt>=K)ans++; } vm ex(2e6,1),r(2e6); FOR(i,1,2e6)ex[i]=i*ex[i-1]; REP(i,2e6)r[i]=1/ex[i]; REP(i,26)seen[i]=0; cnt=0; REP(i,N){ REP(j,S[i]-'a'){ ll c=cnt; if(!seen[j])c++; ll L=M-i-1; ll t=max(0LL,K-c); //0文字~L文字で新たにt種類以上 FOR(k,t,27-c)REP(j,c+1)ans+=DP[L][k+j]*ex[26-c]*r[k]*r[26-c-k]*ex[c]*r[j]*r[c-j]*r[26]*ex[k+j]*ex[26-k-j]; //cout<