C++ :

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,k,a[101][101],dis[101],sum=0,tot=0;
void work(int);
int main()
{
	memset(a,0x7f,sizeof(a));
	cin>>n>>k;
	int x,y,t;
	for(int i=1;i<=k;i++)
	{
		cin>>x>>y>>t;
		a[x][y]=a[y][x]=t;
		tot+=t;
	}
	work(1);
	cout<<tot-sum;
}
void work(int x)
{
	for(int i=1;i<=n;i++) dis[i]=a[x][i];
	dis[x]=0;
	for(int j=1;j<=n;j++)
	{
		int k,mi=0x7f7f7f7f;
		for(int i=1;i<=n;i++)
		{
			if(dis[i]<mi&&dis[i]!=0)
			{
				mi=dis[i];
				k=i;
			}
		}
		sum+=dis[k];
		dis[k]=0;
		for(int i=1;i<=n;i++)
		{
			if(dis[i]>a[k][i]) dis[i]=a[k][i];
		}
	}
}

Pascal :

program wtc;
type
 list=record
  frontv,endv,w:longint;
  end;
var
 n,i,j,s1,s2,k,p,q,min:longint;
 a:array[1..100,1..100]of longint;
 c:array[1..100]of list;
 t:list;
procedure prim;
begin
 for i:= 1 to n-1 do
  begin
   c[i].frontv:=1;
   c[i].endv:=i+1;
   c[i].w:=a[c[i].frontv,c[i].endv];
  end;
 for k:= 1 to n-1 do
  begin
   min:=maxint;
   for i:=k to n-1 do
    if min>c[i].w then
     begin
      min:=c[i].w;
      p:=i;
     end;
   t:=c[p]; c[p]:=c[k]; c[k]:=t;
   j:=c[k].endv;
   for i:= k+1 to n-1 do
    begin
     if a[j,c[i].endv]<c[i].w then
      begin
       c[i].w:=a[j,c[i].endv];
       c[i].frontv:=j;
      end;
    end;
  end;
end;

begin
 readln(n,k);
 for i:= 1 to k do
   begin
    read(p,q);
    read(a[p,q]);
    a[q,p]:=a[p,q];
    s1:=s1+a[p,q];
   end;
 for i:= 1 to n do
  for j:= 1 to n do
    if (i<>j) and (a[i,j]=0) then
     a[i,j]:=maxint;
   prim;
   s2:=0;
 for i:= 1 to n-1 do
  s2:=s2+c[i].w;
  writeln(s1-s2);
end.