Practice Image processing and Loops with the exercise "Hidden Messages In Images"

Learning Opportunities

This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.

Statement

Goal

Steganography in images is to hide information in pixels of images imperceptibly to the human eye. In this problem there are ASCII messages hidden in the image pixels. More specifically, the least significant bit of each pixel represents a piece of the ASCII message.

Every 8 consecutive bits we have a byte, convert that byte into an ASCII value. To make your life easier, images will always have a number of pixels multiple of 8. Print all ASCII characters extracted from the image.

Example
Given an input image with width = 4 and height = 4
106 19 134 22
161 192 98 184
52 51 97 88
208 63 58 25

106 => 01101010 => less significant bit => 0
19 => 00010011 => less significant bit => 1
134 => 10000110 => less significant bit => 0
22 => 00010110 => less significant bit => 0
161 => 10100001 => less significant bit => 1
192 => 11000000 => less significant bit => 0
98 => 01100010 => less significant bit => 0
184 => 10111000 => less significant bit => 0
52 => 00110100 => less significant bit => 0
51 => 00110011 => less significant bit => 1
97 => 01100001 => less significant bit => 1
88 => 01011000 => less significant bit => 0
208 => 11010000 => less significant bit => 0
63 => 00111111 => less significant bit => 1
58 => 00111010 => less significant bit => 0
25 => 00011001 => less significant bit => 1

Extracted bits => 0100100001100101
Split binary information into bytes => [ "01001000", "01100101"]
Map bytes to ASCII => ["H", "e"]

Output => He

Input

Line 1: Two integers w, h for the dimensions of the image.
Next h lines: w space separated integers for the pixels of the image.

Output

ASCII message extracted from the image

Constraints

8 ≤ w,h ≤ 50
w*h % 8 == 0

Example

Input

8 12
220 251 30 182 233 122 150 30
132 101 135 212 246 201 128 203
62 33 39 70 73 175 218 140
44 165 9 140 83 67 34 100
142 75 125 242 49 175 209 37
252 26 123 6 186 72 230 94
218 85 228 205 146 67 219 187
194 159 81 190 51 235 41 121
208 33 245 71 172 218 97 130
122 31 135 198 135 249 174 28
162 109 149 216 156 195 140 10
100 252 1 164 150 22 144 109

Output

Hello World!

Solve it

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