void citire(void)
{

    int a,b,c;

   ...
}

    scanf("%d",&N);
    for(int i=1;i<N;i++)
    {
        scanf("%d %d %d",&a,&b,&c);
        A[a].push_back(make_pair(b,c));
        A[b].push_back(make_pair(a,c));
    }

void sterge(void)
{
   ...

}
inline void DF(int nod)

        }
}

inline void sterge(void)
{
    for(int i=0;i<N;i++)
        A[i].clear(), Fii[i] = T[i] = viz[i] = Suma = 0;
}
 

int main()
{
    int T;

        printf("%lf\n",(double)(Suma/((ll)N*(N-1)/2)));
        sterge();
    }

 
    return 0;

}
==