program rebuild;
const
  maxtin=1000000;
var
  i,j,k,n,m,sum,min,a,b,c,d,s,e:longint;
  map:array[1..100,0..100]of longint;
  bad,f,w:array[1..100,1..100]of longint;
  bool:array[1..100]of boolean;
procedure init;
begin
  assign(input,'rebuild.in');
  reset(input);
  assign(output,'rebuild.out');
  rewrite(output);
  read(n,m);
  for i:=1 to n do
    for j:=1 to n do
      if i<>j then
      begin
        f[i,j]:=maxtin;
        w[i,j]:=maxtin
      end;
  for i:=1 to m do
  begin
    read(a,b,c);
    f[a,b]:=c;
    w[a,b]:=c;
    inc(map[a,0]);
    map[a,map[a,0]]:=b;
    f[b,a]:=c;
    w[b,a]:=c;
    inc(map[b,0]);
    map[b,map[b,0]]:=a
  end;
  read(d);
  for i:=1 to d do
  begin
    read(a,b);
    bad[a,b]:=1;
    bad[b,a]:=1
  end;
  read(s,e);
  fillchar(bool,sizeof(bool),true);
  bool[s]:=false;
  min:=maxtin
end;

procedure floyd;
begin
  for k:=1 to n do
    for i:=1 to n do
      for j:=1 to n do
        if i<>j then
          if f[i,j]>f[i,k]+f[k,j] then
      	    f[i,j]:=f[i,k]+f[k,j]
end;

procedure dfs(vet:longint);
var
  l:longint;
begin
  if vet=e then
  begin
    if sum<min then
      min:=sum
  end
  else
    for l:=1 to map[vet,0] do
      if (f[map[vet,l],e]<maxtin) and bool[map[vet,l]] then
      begin
        if bad[vet,map[vet,l]]=1 then
      	  sum:=sum+w[vet,map[vet,l]];
      	bool[map[vet,l]]:=false;
       	dfs(map[vet,l]);
        if bad[vet,map[vet,l]]=1 then
       	  sum:=sum-w[vet,map[vet,l]];
       	bool[map[vet,l]]:=true;
      end
end;

procedure print;
begin
  writeln(min);
  close(input);
  close(output)
end;

begin
  init;
  floyd;
  dfs(s);
  print
end.