[模板]矩阵乘

block operator*(block a,block b){
    block zz;memset(zz.x,0,sizeof(zz.x));
    for(int i=1;i<=4;++i)for(int j=1;j<=4;++j)for(int k=1;k<=4;++k)
        zz.x[i][j]=(zz.x[i][j]+a.x[i][k]*b.x[k][j]%m)%m;
    return zz;
}