output_description: Print the total weight of the minimum spanning tree of $G$.
input_description: In the first line, an integer $n$ denoting the number of vertices in $G$ is
  given. In the following $n$ lines, a $n \times n$ adjacency matrix $A$ which
  represents $G$ is given. $a_{ij}$ denotes the weight of edge connecting vertex
  $i$ and vertex $j$. If there is no edge between $i$ and $j$, $a_{ij}$ is given
  by -1.
problem_description: Minimum Spanning Tree
  
  For a given weighted graph $G = (V, E)$, find the minimum spanning tree (MST)
  of $G$ and print total weight of edges belong to the MST.
samples: [{"input": "5\n     -1 2 3 1 -1\n     2 -1 -1 4 -1\n     3 -1 -1 1 1\n     1 4 1 -1 3\n     -1 -1 1 3 -1", "output": "5"}]