output_description: Print the shortest distance in a line. If there is no solution, print -1.
input_description: |V| |E|
      s0 t0 d0
      s1 t1 d1
      :
      s|E|-1 t|E|-1 d|E|-1
      
  
  |V| is the number of vertices and |E| is the number of edges in the graph. The
  graph vertices are named with the numbers 0, 1,..., |V|-1 respectively.
  
  si and ti represent source and target vertices of i-th edge (directed) and di
  represents the distance between si and ti (the i-th edge).
attempt: INF = 10**18
  n, m = map(int, input().split())
  dist = [[INF for _ in range(n)] for _ in range(n)]
  dp = [[INF for _ in range(n + 1)] for _ in range(1 << n)]
  for _ in range(m):
      a, b, c = map(int, input().split())
      dist[a][b] = c
  dp[(1 << n) - 1][0] = 0
  for bit in range((1 << n) - 2, -1, -1):
      for v in range(n):
          for u in range(n):
              if not ((bit >> u) & 1):
                  dp[bit][v] = min(dp[bit][v], dp[bit | 1 << u][u] + dist[u][v])
  print(dp[0][0] if dp[0][0] != INF else -1)
  
problem_description: Traveling Salesman Problem
  
    
  
  For a given weighted directed graph G(V, E), find the distance of the shortest
  route that meets the following criteria:
  
    * It is a closed cycle where it ends at the same point it starts.
    * It visits each vertex exactly once.
samples: [{"input": "4 6\n    0 1 2\n    1 2 3\n    1 3 9\n    2 0 1\n    2 3 6\n    3 2 4", "output": "16"}, {"input": "3 3\n    0 1 1\n    1 2 1\n    0 2 1", "output": "-1"}]