grade_dict = {}
with open("p086_grade.txt", encoding="utf8") as f:
  for line in f:
    sno, grade = line.strip().split(",")
    grade_dict[sno] = grade

print(grade_dict)

fout = open("p086.txt", "w", encoding="utf8")
with open("p086_student.txt", encoding="utf8") as f:
  for line in f:
    sno, sname = line.strip().split(",")
    grade = grade_dict[sno]
    fout.write(f"{sno},{sname},{grade}\n")
fout.close()