output_description: If there exists a maximum value of the score that can be obtained, print that
  maximum value; otherwise, print `-1`.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N M P
      A_1 B_1 C_1
      :
      A_M B_M C_M
attempt: from collections import deque  # ,defaultdict
  
  printn = lambda x: print(x, end="")
  inn = lambda: int(input())
  inl = lambda: list(map(int, input().split()))
  inm = lambda: map(int, input().split())
  ins = lambda: input().strip()
  DBG = True and False
  BIG = 10**18
  R = 10**9 + 7
  
  
  def ddprint(x):
      if DBG:
          print(x)
  
  
  n, m, p = inm()
  dst = [{} for i in range(n + 1)]
  src = [{} for i in range(n + 1)]
  es = []
  for i in range(m):
      a, b, c = inm()
      dst[a][b] = src[b][a] = p - c
      es.append((a, b, p - c))
  
  rf1 = [False] * (n + 1)
  rf1[1] = True
  q = deque([1])
  while len(q) > 0:
      x = q.popleft()
      for y in dst[x]:
          if not rf1[y]:
              rf1[y] = True
              q.append(y)
  
  rtn = [False] * (n + 1)
  rtn[n] = True
  q = deque([n])
  while len(q) > 0:
      x = q.popleft()
      for y in src[x]:
          if not rtn[y]:
              rtn[y] = True
              q.append(y)
  
  ddprint(rf1)
  ddprint(rtn)
  
  use = [rf1[i] and rtn[i] for i in range(n + 1)]
  
  es = [z for z in es if use[z[0]] and use[z[1]]]
  ddprint(es)
  
  dp = [BIG] * (n + 1)
  dp[1] = 0
  for i in range(n):
      ddprint(dp)
      for a, b, c in es:
          if dp[b] > dp[a] + c:
              dp[b] = dp[a] + c
              if i == n - 1:
                  print(-1)
                  exit()
  
  print(max(0, -dp[n]))
  
problem_description: Statement
  
  There is a directed graph with N vertices numbered 1 to N and M edges. The
  i-th edge is directed from Vertex A_i to Vertex B_i, and there are C_i coins
  placed along that edge. Additionally, there is a button on Vertex N.
  
  We will play a game on this graph. You start the game on Vertex 1 with zero
  coins, and head for Vertex N by traversing the edges while collecting coins.
  It takes one minute to traverse an edge, and you can collect the coins placed
  along the edge each time you traverse it. As usual in games, even if you
  traverse an edge once and collect the coins, the same number of coins will
  reappear next time you traverse that edge, which you can collect again.
  
  When you reach Vertex N, you can end the game by pressing the button. (You can
  also choose to leave Vertex N without pressing the button and continue
  traveling.) However, when you end the game, you will be asked to pay T \times
  P coins, where T is the number of minutes elapsed since the start of the game.
  If you have less than T \times P coins, you will have to pay all of your coins
  instead.
  
  Your score will be the number of coins you have after this payment. Determine
  if there exists a maximum value of the score that can be obtained. If the
  answer is yes, find that maximum value.
samples: [{"input": "3 3 10\n    1 2 20\n    2 3 30\n    1 3 45", "output": "35\n    \n\n![Figure of the graph given in Sample Input\n1](https://img.atcoder.jp/ghi/5cb074e2d7c3282da137ac4ab2fbc700.png)\n\nThere are two ways to travel from Vertex 1 to Vertex 3:\n\n  * Vertex 1 \\rightarrow 2 \\rightarrow 3: You collect 20 + 30 = 50 coins on the way. After two minutes from the start of the game, you press the button, pay 2 \\times 10 = 20 coins, and you have 50 - 20 = 30 coins left.\n  * Vertex 1 \\rightarrow 2: You collect 45 coins on the way. After one minute from the start of the game, you press the button, pay 1 \\times 10 = 10 coins, and you have 45 - 10 = 35 coins left.\n\nThus, the maximum score that can be obtained is 35.\n\n* * *"}, {"input": "2 2 10\n    1 2 100\n    2 2 100", "output": "-1\n    \n\n![Figure of the graph given in Sample Input\n2](https://img.atcoder.jp/ghi/eb2188ad1e8189f963d233415fb293b6.png)\n\nThe edge extending from Vertex 1 takes you to Vertex 2. If you then traverse\nthe edge extending from Vertex 2 to itself t times and press the button, your\nscore will be 90 + 90t. Thus, you can infinitely increase your score, which\nmeans there is no maximum value of the score that can be obtained.\n\n* * *"}, {"input": "4 5 10\n    1 2 1\n    1 4 1\n    3 4 1\n    2 2 100\n    3 3 100", "output": "0\n    \n\n![Figure of the graph given in Sample Input\n3](https://img.atcoder.jp/ghi/217f7a224b80a05d8e25140c57e65ae7.png)\n\nThere is no way to travel from Vertex 1 to Vertex 4 other than traversing the\nedge leading from Vertex 1 to Vertex 4 directly. You will pick up one coin\nalong this edge, but after being asked to paying 10 coins, your score will be\n0.\n\nNote that you can collect an infinite number of coins if you traverse the edge\nleading from Vertex 1 to Vertex 2, but this is pointless since you can no\nlonger reach Vertex 4 and end the game."}]