# VC - 50Problem:```There are files A.png and B.png. But where's the flag?A.pngB.png```For file A.png and B.png I've checked for file type and [Exiftool](http://www.sno.phy.queensu.ca/~phil/exiftool/) but there are nothing suspicious. 
```root@AIRBUS:# exiftool A.png ExifTool Version Number         : 10.47File Name                       : A.pngDirectory                       : .File Size                       : 17 kBFile Modification Date/Time     : 2017:03:24 16:19:58-04:00File Access Date/Time           : 2017:03:26 09:06:54-04:00File Inode Change Date/Time     : 2017:03:25 08:55:06-04:00File Permissions                : rw-r--r--File Type                       : PNGFile Type Extension             : pngMIME Type                       : image/pngImage Width                     : 370Image Height                    : 370Bit Depth                       : 1Color Type                      : GrayscaleCompression                     : Deflate/InflateFilter                          : AdaptiveInterlace                       : NoninterlacedImage Size                      : 370x370Megapixels                      : 0.137root@AIRBUS:# exiftool B.png ExifTool Version Number         : 10.47File Name                       : B.pngDirectory                       : .File Size                       : 17 kBFile Modification Date/Time     : 2017:03:24 16:20:02-04:00File Access Date/Time           : 2017:03:26 11:33:38-04:00File Inode Change Date/Time     : 2017:03:25 08:55:06-04:00File Permissions                : rw-r--r--File Type                       : PNGFile Type Extension             : pngMIME Type                       : image/pngImage Width                     : 370Image Height                    : 370Bit Depth                       : 1Color Type                      : GrayscaleCompression                     : Deflate/InflateFilter                          : AdaptiveInterlace                       : NoninterlacedImage Size                      : 370x370Megapixels                      : 0.137root@AIRBUS:# ```Both of them are Grayscale image that mean no color applied to the images. I check for color by reading the images and printing the pixel value of them using python code. ```pythonfrom PIL import Imageim = Image.open("A.png","r")pix_val = list(im.getdata())for x in pix_val:	print x```
I found that there are only 2 values 0 and 255. I merge 2 images using python again.```pythonimport Image
with open('pixA.txt') as f:    linesA = f.read().splitlines()
with open('pixB.txt') as f:    linesB = f.read().splitlines()
int_listA = [int(i) for i in linesA]int_listB = [int(i) for i in linesB]int_listC = []for i in range(0,len(int_listA)):	C = 255	if int_listA[i] != int_listB[i]:		C = 0	int_listC.append(C)
# print int_listim = Image.new('L', (370, 370))im.putdata(int_listC)im.save('solve.png')```Now I found the flag.![flag](kapi-files/solve.png)
The flag was:* VolgaCTF{Classic_secret_sharing_scheme}