ll@++N,@M,@A[2N-1],b[N]{},t;VI S(M),D;rep(i,M){ll@s;b[s]=1;S[i]=s;}D=S;rep(N){VI E;rep[S](i,M)REP[D](j,D.size())if(!b[t=A[i+j]])b[t]=1,E.push_back(t);D=E;}wt(sum[i,0,N](b[i]));