#include<bits/stdc++.h>
using namespace std;
class Graph
{
int V ;
list < int > *adj;
public :
Graph( int V )
{
this->V = V ;
adj = new list<int>[V];
}
void addEdge ( int u, int v ) ;
int countEdges () ;
};
void Graph :: addEdge ( int u, int v )
{
adj[u].push_back(v);
adj[v].push_back(u);
}
int Graph :: countEdges()
{
int sum = 0;
for (int i = 0 ; i < V ; i++)
sum += adj[i].size();
return sum/2;
}
int main()
{
int V = 9 ;
Graph g(V);
g.addEdge(0, 1 );
g.addEdge(0, 7 );
g.addEdge(1, 2 );
g.addEdge(1, 7 );
g.addEdge(2, 3 );
g.addEdge(2, 8 );
g.addEdge(2, 5 );
g.addEdge(3, 4 );
g.addEdge(3, 5 );
g.addEdge(4, 5 );
g.addEdge(5, 6 );
g.addEdge(6, 7 );
g.addEdge(6, 8 );
g.addEdge(7, 8 );
cout << g.countEdges() << endl;
return 0;
}