program heatwvx;
var
  t,c,ts,te,a,b,c1,i,j:longint;
  tab:array[1..2500,1..2500]of longint;
procedure dijkstra;
var
  flag:array[1..2500]of boolean;
  w,x,i,j,min,minn:longint;
begin
  fillchar(flag,sizeof(flag),false);
  flag[ts]:=true;
  minn:=ts;
  for x:=2 to t do
  begin
    min:=2147483647;
    for i:=1 to t do
      if (tab[ts,i]<min)and(flag[i]=false) then
      begin
        min:=tab[ts,i];
        minn:=i;
      end;
   flag[minn]:=true;
   for j:=1 to t do
     if (j<>minn) and (tab[ts,minn]+tab[minn,j]<tab[ts,j]) and(flag[j]=false) then
       tab[ts,j]:=tab[ts,minn]+tab[minn,j];
   end;
   write(tab[ts,te],' ');
end;
begin
  assign(input,'heatwvx.in');
  assign(output,'heatwvx.out');
  reset(input);
  rewrite(output);
  readln(t,c,ts,te);
  for i:=1 to t do
    for j:=1 to t do
      tab[i,j]:=2000000000;
  for i:=1 to c do
  begin
    readln(a,b,c1);
    tab[a,b]:=c1;
    tab[b,a]:=c1;
  end;
  dijkstra;
  close(input);
  close(output);
end.