We were provided with a bulk of 1,207 face images. After an initial quick glance look into all images,we solved this challenge most probably in a non-intended way. By running `exiftool` against all imagesand sorting the results by number of repetitions, attribute `Exif Byte Order` stood out:
```shexiftool * | sort |  uniq -c | sort -n
...      1 ======== 999.jpg      1 ======== 99.jpg      1 ======== 9.jpg      1 Exif Byte Order                 : Big-endian (Motorola, MM)      1 File Modification Date/Time     : 2020:06:06 21:39:50+02:00      1 File Name                       : 0.jpg      1 File Name                       : 1000.jpg...
```
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For a bulk of images, which all should be preprocessed in an uniform way, this was quite "interesting". Insubsequent run found that the corresponding image was `1145.jpg`:
```$ exiftool * | grep -C 15 "Exif Byte Order"Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)Image Size                      : 2444x1718Megapixels                      : 4.2======== 1145.jpgExifTool Version Number         : 11.88File Name                       : 1145.jpgDirectory                       : .File Size                       : 56 kBFile Modification Date/Time     : 2020:06:06 21:39:50+02:00File Access Date/Time           : 2020:07:03 13:51:49+02:00File Inode Change Date/Time     : 2020:07:02 12:18:18+02:00File Permissions                : rw-r--r--File Type                       : JPEGFile Type Extension             : jpgMIME Type                       : image/jpegExif Byte Order                 : Big-endian (Motorola, MM)Orientation                     : Horizontal (normal)X Resolution                    : 300Y Resolution                    : 300Resolution Unit                 : inchesJFIF Version                    : 1.01Image Width                     : 2444Image Height                    : 1718Encoding Process                : Baseline DCT, Huffman codingBits Per Sample                 : 8Color Components                : 3Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)Image Size                      : 2444x1718Megapixels                      : 4.2======== 1146.jpgExifTool Version Number         : 11.88```
----
Flag (`cscml2020{ml_can_be_learned_easily_by_examples}`) is visible at the bottom of the image (`1145.jpg`):
![1145.jpg](https://i.imgur.com/thMLMm2.jpg)