z55250825

program kruskal;
var
n,m:longint;
a,b,c:array[1..100000]of int64;
ans:int64;
f,d:array[1..100000]of longint;

function find(x:longint):longint;
begin
  if f[x]=x then exit(x);
  f[x]:=find(f[x]);
  exit(f[x]);
end;

procedure union(a,b:longint);
var x,y:longint;
begin
  x:=find(a);y:=find(b);
  if x=y then exit;
  if d[x]<=d[y] then
   begin
     f[x]:=y;
     d[y]:=d[x]+d[y];
    end
   else
    begin
     f[y]:=x;
     d[x]:=d[x]+d[y];
    end;
end;

procedure swap(var a,b:int64);
var c:int64;
begin
  c:=a;a:=b;b:=c;
end;

procedure qsort(l,r:longint);
var i,j:longint;
    x,y:int64;
begin
  i:=l;j:=r;
  x:=c[(l+r)shr 1];
  repeat
    while c[i]<x do inc(i);
    while c[j]>x do dec(j);
    if i<=j then begin
      swap(c[i],c[j]);
      swap(a[i],a[j]);
      swap(b[i],b[j]);
      inc(i);dec(j);
     end;
  until i>j;
  if i<r then qsort(i,r);
  if j>l then qsort(l,j);
end;

procedure main;//kruskal;
var i,j:longint;
begin
  qsort(1,m);
  for i:=1 to n do f[i]:=i;
  for i:=1 to n do d[i]:=1;
  j:=0;
  ans:=0;
  for i:=1 to m do
      if find(a[i])<>find(b[i]) then 
      begin
      inc(ans,c[i]);
      inc(j);
      union(a[i],b[i]);
      if j=n-1 then break;
      end;
  write(ans);
end;

procedure init;
var i:longint;
begin
  read(n);read(m);
  for i:=1 to m do
    begin
      read(a[i]);read(b[i]);read(c[i]);
    end;
end;
begin
  init;
  main;
end.