def add_index_to_vtt(vtt_file):
    with open(vtt_file, 'r') as file:
        lines = file.readlines()

    # Remove the existing index
    lines = [line.strip() for line in lines if not line.strip().isdigit()]

    # Add new index
    new_lines = []
    for i in range(len(lines)):
        if '-->' in lines[i]:
            print(i)
            new_lines.append(f'{(i)-1}\n{lines[i]}')
        else:
            new_lines.append(lines[i])

    # Write the modified VTT file
    with open(vtt_file, 'w') as file:
        file.write('\n'.join(new_lines))

# Usage example
vtt_file_path = 'es.new_tarik_lward_output.vtt'
add_index_to_vtt(vtt_file_path)