Extract poscar files from traj.xyz

This python script extract poscar files from traj.xyz lattice constants are getton from CuC.xsf file

#lipai@mail.ustc.edu.cn
    import os
    f0=open("CuC.xsf")
    f0.readline()
    f0.readline()
    x=f0.readline()
    y=f0.readline()
    z=f0.readline()
    f0.close()
    num_Cu=72

    f1=open("traj.xyz")
    ordi=1
    while 1:
            a=f1.readline()
            if not a:
                    break
            num=int(a.split()[0])
            fileout="POSCAR-"+str(ordi)
            f2=open(fileout,"w")
            f2.write("Cu & C system from GCMC simulation\n")
            f2.write("1.0\n")
            f2.write(x)
            f2.write(y)
            f2.write(z)
            f2.write("Cu    C\n")
            f2.write(str(num_Cu)+"  "+str(num-num_Cu))
            f2.write("\nCart\n")
            ordi+=1

            f1.readline()
            for i in range(0,num):
                    a=f1.readline().split()
                    f2.write(a[1]+"\t"+a[2]+"\t"+a[3]+"\n")

            f2.close()

    f1.close()

    os.system('mkdir poscar')
    os.system('mv POSCAR*  poscar')