10  
    1    2    2 0.    
    1    3    2 0.
    2    1    2 0.
    2    3    2 0.
    7    3    1 -30000.
    8    3    1 -30000.
   19    1    2 0.
   19    3    2 0.
   20    2    2 0.
   20    3    2 0.