Segmentation Fault
    # include <iostream>
    # include <vector>

    using namespace std;

    typedef struct node
    {
	int city;
	int cost;
	node (int x, int y ):
		city(x),cost(y){}
    } Node;


    int main()
    {
    	vector < vector < Node > > Vec;
    	int edges, edgecost;
    	int num_of_vertices;
    	int start_vertex, end_vertex;
    
    	cin >> num_of_vertices >> edges ;
    
    	for ( int I=0; I <edges; I++)
    	{
    		cin >> start_vertex;
    		cin >> end_vertex;
    		cin >> edgecost;
    		Vec[start_vertex].push_back(Node (end_vertex,edgecost));
    	}
    	return 0;
    }


Segmentation Fault
===

    # include <iostream>
    # include <vector>

    using namespace std;

    typedef struct node
    {
	int city;
	int cost;
	node (int x, int y ):
		city(x),cost(y){}
    } Node;


    int main()
    {
    	vector < vector < Node > > Vec;
    	int edges, edgecost;
    	int num_of_vertices;
    	int start_vertex, end_vertex;
    
    	cin >> num_of_vertices >> edges ;
    
    	for ( int I=0; I <edges; I++)
    	{
    		cin >> start_vertex;
    		cin >> end_vertex;
    		cin >> edgecost;
    		Vec[start_vertex].push_back(Node (end_vertex,edgecost));
    	}
    	return 0;
    }

