program daluchongjian;
var
  a,b,c,d,k,i,j,x,y,n,m:longint;
  map:array[1..1000,1..1000]of longint;
  bz:array[1..1000,1..1000]of boolean;
begin
  assign (input,'rebuild.in');
  reset(input);
  assign (output,'rebuild.out');
  rewrite (output);
    readln (n);
    readln (m);
    for i:=1 to n do
      for j:=1 to n do
        map[i,j]:=maxlongint;
    for i:=1 to n  do
      for j:=1 to n do
        bz[i,j]:=false;
    for i:=1 to m do
    begin
      readln (a,b,c);
      bz[a,b]:=true;
      bz[b,a]:=true;
      map[a,b]:=c;
      map[b,a]:=c
    end;
    readln (d);
    for i:=1 to d do
    begin
      readln (a,b);
      bz[a,b]:=false;
      bz[b,a]:=false
    end;
    for i:=1 to n do
      for j:=1 to n do
        if bz[i,j] then
          map[i,j]:=0;
    readln (x,y);
    for k:=1 to n do
      for i:=1 to n do
        for j:=1 to n do
          if (map[i,k]<>maxlongint)and(map[k,j]<>maxlongint)
          and(map[i,k]+map[k,j]<map[i,j]) then
            map[i,j]:=map[i,k]+map[k,j];
    writeln (map[x,y]);
  close (input);
  close (output)
end.