Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/py_compile.py", line 117, in compile
    raise py_exc
py_compile.PyCompileError:   File "/in/foo.py", line 4
    price=float(input(f"请输入购买的第{i}种图书的价格(元):"))
                                                                        ^
SyntaxError: invalid syntax