output_description: If there exists a set of values (x_1, x_2, ..., x_N) that is consistent with
  all given pieces of information, print `Yes`; if it does not exist, print
  `No`.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N M
      L_1 R_1 D_1
      L_2 R_2 D_2
      :
      L_M R_M D_M
attempt: comp = [False] * (N + 1)
  
  cond = True
  hold = []
  
  for i in range(M):
      l = new_LRD[i][0]
      r = new_LRD[i][1]
      d = new_LRD[i][2]
      if i == 0:
          comp[l] = 0
          comp[r] = d     
      else:
          if not isinstance(comp[l], bool):
              if isinstance(comp[r], bool):
                    comp[r] = (comp[l] + d)
              else:
                  if comp[r] != (comp[l] + d):
                      cond = False
                      break
                      
          else:
              if not isinstance(comp[r], bool):
                  comp[l] = (comp[r] - d)
                  
              else:
                  hold.append([l, r, d])
                  
  
  for i in range(len(hold)):
      l = hold[i][0]
      r = hold[i][1]
      d = hold[i][2]    
          if not isinstance(comp[l], bool):
              if isinstance(comp[r], bool):
                    comp[r] = (comp[l] + d)
              else:
                  if comp[r] != (comp[l] + d):
                      cond = False
                      break
                      
          else:
              if not isinstance(comp[r], bool):
                  comp[l] = (comp[r] - d)
                  
              else:
                  continue
  
  
  if cond:
      print('Yes')
  else:
      print('No')
problem_description: Statement
  
  There are N people standing on the x-axis. Let the coordinate of Person i be
  x_i. For every i, x_i is an integer between 0 and 10^9 (inclusive). It is
  possible that more than one person is standing at the same coordinate.
  
  You will given M pieces of information regarding the positions of these
  people. The i-th piece of information has the form (L_i, R_i, D_i). This means
  that Person R_i is to the right of Person L_i by D_i units of distance, that
  is, x_{R_i} - x_{L_i} = D_i holds.
  
  It turns out that some of these M pieces of information may be incorrect.
  Determine if there exists a set of values (x_1, x_2, ..., x_N) that is
  consistent with the given pieces of information.
samples: [{"input": "3 3\n    1 2 1\n    2 3 1\n    1 3 2", "output": "Yes\n    \n\nSome possible sets of values (x_1, x_2, x_3) are (0, 1, 2) and (101, 102,\n103).\n\n* * *"}, {"input": "3 3\n    1 2 1\n    2 3 1\n    1 3 5", "output": "No\n    \n\nIf the first two pieces of information are correct, x_3 - x_1 = 2 holds, which\nis contradictory to the last piece of information.\n\n* * *"}, {"input": "4 3\n    2 1 1\n    2 3 5\n    3 4 2", "output": "Yes\n    \n\n* * *"}, {"input": "10 3\n    8 7 100\n    7 9 100\n    9 8 100", "output": "No\n    \n\n* * *"}, {"input": "100 0", "output": "Yes"}]