 ""

  N ,       . 
 ,         . 
       .    
    N-,      .

 
      N (1<=N<=100),   
N , i-       
i-  (       0  100). 
   M -    ,    
 .      -  , 
  .    (     
   ,     ),     
    ,   ,  
   .

 
      -    
 -1,   .

  
4
1 10 2 15
4
1 2 1 3 4 2 4 3

  
3


  -  1-    3-,    4-. 
    1  3 .

  
4
1 10 2 15
0

  
-1


 

