#include #include #include int I[]={-1,1,5,-1,7,2,-1,4,8}; char Fk[10000001]; int Fz[10000001]; void z(int n,int *n_,int *r_){ int r=0; for(;n%3==0;n/=3)r++; *n_=n,*r_=r; } int comb(int n,int k){ char k0=Fk[n],k1=Fk[k],k2=Fk[n-k]; int z0=Fz[n],z1=Fz[k],z2=Fz[n-k]; int z=z0-z1-z2,r=(int)k0*I[k1]*I[k2]%9; return z==0 ? r : z==1 ? r*3%9 : 0; } int main(){ int i; Fk[0]=1,Fz[0]=0; for(i=1;i<=10000000;i++){ char k0=(Fk[(i-1)/2]>>((i-1)%2^1)*4)&0xf; int z0=Fz[i-1]; int k1,z1; z(i,&k1,&z1); Fk[i/2]|=(k0*k1%9)<