#include #include #include using namespace std; using mint=atcoder::modint998244353; int N; string S; main() { cin>>N>>S; vectorI(N),J(N); for(int i=0;iK=convolution(I,J); vectorA(N-1); mint p=1; for(int i=0;iB(N-1); vectorinv(N-1); p=1/p; for(int i=N-2;i>=0;i--) { B[N-2-i]=p*=i+1; inv[i]=p; } vectorC=convolution(A,B); int ans=0; for(int k=0;k