Problem Statement  
There is a community of art lovers who meet from time to time and trade images with each other. Each image transaction must obey the following rules:
 
Definition  
 
Constraints  
  price will contain exactly N elements, where N is between 2 and 15, inclusive.  
  Each element of price will contain exactly N characters.  
  Each element of price will contain only digits ('0''9').  
Examples  
0)  
 
1)  
 
2)  
 
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4)  
