ファイルb'train.csv 'は、ファイルが存在するのに存在しません

コード：

import pandas as pd
train_df = pd.read_csv("train.csv")

エラー：

FileNotFoundError                   Traceback (most recent call last)
    <ipython-input-17-05c7c432b69f> in <module>()
      1 import pandas as pd
      2 
    ----> 3 train_df = pd.read_csv("../input/train.csv")

    /anaconda3/lib/python3.6/site-packages/pandas/io/parsers.py in parser_f(filepath_or_buffer, sep, delimiter, header, names, index_col, usecols, squeeze, prefix, mangle_dupe_cols, dtype, engine, converters, true_values, false_values, skipinitialspace, skiprows, nrows, na_values, keep_default_na, na_filter, verbose, skip_blank_lines, parse_dates, infer_datetime_format, keep_date_col, date_parser, dayfirst, iterator, chunksize, compression, thousands, decimal, lineterminator, quotechar, quoting, escapechar, comment, encoding, dialect, tupleize_cols, error_bad_lines, warn_bad_lines, skipfooter, skip_footer, doublequote, delim_whitespace, as_recarray, compact_ints, use_unsigned, low_memory, buffer_lines, memory_map, float_precision)
    707                     skip_blank_lines=skip_blank_lines)
    708 
    --> 709         return _read(filepath_or_buffer, kwds)
    710 
    711     parser_f.__name__ = name

    /anaconda3/lib/python3.6/site-packages/pandas/io/parsers.py in _read(filepath_or_buffer, kwds)
    447 
    448     # Create the parser.
    --> 449     parser = TextFileReader(filepath_or_buffer, **kwds)
    450 
    451     if chunksize or iterator:

    /anaconda3/lib/python3.6/site-packages/pandas/io/parsers.py in __init__(self, f, engine, **kwds)
    816             self.options['has_index_names'] = kwds['has_index_names']
    817 
    --> 818         self._make_engine(self.engine)
    819 
    820     def close(self):

    /anaconda3/lib/python3.6/site-packages/pandas/io/parsers.py in _make_engine(self, engine)
    1047     def _make_engine(self, engine='c'):
    1048         if engine == 'c':
    -> 1049             self._engine = CParserWrapper(self.f, **self.options)
    1050         else:
    1051             if engine == 'python':

    /anaconda3/lib/python3.6/site-packages/pandas/io/parsers.py in __init__(self, src, **kwds)
    1693         kwds['allow_leading_cols'] = self.index_col is not False
    1694 
    -> 1695         self._reader = parsers.TextReader(src, **kwds)
    1696 
    1697         # XXX

    pandas/_libs/parsers.pyx in pandas._libs.parsers.TextReader.__cinit__()

    pandas/_libs/parsers.pyx in      pandas._libs.parsers.TextReader._setup_parser_source()

FileNotFoundError: File b'../input/train.csv' does not exist

助けてください！使ってみましpd.read_csv("../input/train.csv")たが、まだエラーがあります。私はJupyterノートブックを使用しているMacユーザーです。