import java.util.LinkedList;
import java.util.Scanner;
import java.util.Iterator;

class Graph {
	private int totalVertex;
	//adjMatrix[u][v] = 1 if there is an edge from u to v, otherwise 0
	private int[][] adjMatrix;
	//adjWeight[u][v] -- the weight of the edge from u to v if there is one
	private int[][] adjWeight;
	//if a node is settled (e.g., processed in the Dijkstra's algorithm)
	private Boolean[] ifSettled;
	public Graph() { totalVertex = 0; }
	public int getTotalVertex() { return totalVertex; }
	//load graph from standard input
	public void loadAdjMatrix() {
		Scanner in = new Scanner(System.in);
		totalVertex = in.nextInt();
		adjMatrix = new int[totalVertex][totalVertex];
		adjWeight = new int[totalVertex][totalVertex];
		ifSettled = new Boolean[totalVertex];
		int i, j;
		for(i = 0; i < totalVertex; i ++) {
			ifSettled[i] = false;
			for(j = 0; j < totalVertex; j ++) {
				adjMatrix[i][j] = adjWeight[i][j] = 0;
			}
		}
		int u, v;
		for(i = 0; i < totalVertex; i ++) {
			for(j = 0; j < totalVertex; j ++) {
				v = in.nextInt(); 
				if(v != -1) {adjMatrix[i][j] = 1;
				adjWeight[i][j] = v; }
			}	
		}
		in.close();
	}
	//return weight of the edge from u to v if there is one
	public int getWeight(int u, int v) {
		return adjWeight[u][v];
	}
	//return neighbors of u as a LinkedList
	public LinkedList<Integer> getNeighbors(int u) {
		LinkedList<Integer> tmp = new LinkedList<Integer>();
		for(int v = 0; v < totalVertex; v ++) {
			if(adjMatrix[u][v] == 1) tmp.add(v);
		}
		return tmp;
	}
	//return unsettled neighbors of u as a LinkedList
	public LinkedList<Integer> getUnsettledNeighbors(int u) {
		LinkedList<Integer> tmp = new LinkedList<Integer>();
		for(int v = 0; v < totalVertex; v ++) {
			if((adjMatrix[u][v] == 1) && (ifSettled[v] == false)) tmp.add(v);
		}
		return tmp;
	}
	//return the unsettled node that has the smallest dist
	public int getUnsettledNearest(int[] dist) {
		int md = Integer.MAX_VALUE;
		int mv = -1;
		int v;
		for(v = 0; v < totalVertex; v ++) {
			if((ifSettled[v] == false) && (dist[v] < md)) {
				md = dist[v];
				mv = v;
			}
		}
		return mv;
	}
	//implement the following	
	public int Dijkstra(int s) {
                  int[] dist = new int[totalVertex];
                  for(int i=0;i<totalVertex;i++){
                      dist[i] = Integer.MAX_VALUE;
                
                  }
                  dist[s] = 0;
                  LinkedList<Integer> q = new LinkedList<Integer>();
                  
                  while(q.size()!=totalVertex){
                      int node = getUnsettledNearest(dist);
                      if(dist[node] == Integer.MAX_VALUE) break;
                      ifSettled[node] = true;
                      q.add(node);
                      LinkedList<Integer> neighbors = getUnsettledNeighbors(node);
                      Iterator<Integer> nb = neighbors.iterator();
                      while(nb.hasNext()){
                          int v = nb.next();
                          int new_dist = getWeight(node, v);
                          if(new_dist < dist[v])
                            dist[v] = new_dist;
                          
                      }
                            
                    
                  }
                  int sum = 0;
                  for(int i = 0;i<totalVertex;i++){
                  		if(dist[i]!=Integer.MAX_VALUE) sum += dist[i];
                  }
                  return sum;
}

	
}
public class Main {
	public static void main(String[] argv) {
		Graph g = new Graph();
		g.loadAdjMatrix();
		int dist = g.Dijkstra(0);
		
			System.out.println(dist);
		
	}
}



Measured memory_bytes: 41308