" "

    " ".  
  N ,   1  N, 
     .    
 ,       
,    .    
   1,  -   N.   
           
   (       ). 
    .

 .        N 
(1 <= N <= 2000) -    M (1 <= M <= 10000) - 
 .     M    
 -  ,         , 
   ,       
   (      10000). 
       ,    
    .

 .     ":)" -    
   , ":(" - 
   ,    
    .

.

input.txt	
2 2
1 2 5
1 2 -5	

output.txt
5
