program rebuild;
  var
    i,j,n,m,t,total,ans,k,x,y,d,s1,s2:longint;
    a:array[0..10000,0..3] of longint;
    f:array[0..10000] of boolean;
    b:array[0..500,0..500] of longint;
  procedure find(x,y:longint);
    var
      i,j:longint;
    begin
      for i:=1 to m do
        if ((x=a[i,1])and(y=a[i,2]))or((x=a[i,2])and(y=a[i,1])) then
          begin
            f[i]:=true;
            exit;
          end;
    end;
  begin
    assign(input,'rebuild.in');reset(input);
    assign(output,'rebuild.out');rewrite(output);
    fillchar(b,sizeof(b),10);
    fillchar(f,sizeof(f),false);
    readln(n);
    readln(m);
    for i:=1 to m do
      for j:=1 to 3 do
        read(a[i,j]);
    readln(d);
    for i:=1 to d do
      begin
        readln(x,y);
        find(x,y);
      end;
    readln(s1,s2);
    for i:=1 to m do
      if f[i] then
        begin
          b[a[i,1],a[i,2]]:=a[i,3];
          b[a[i,2],a[i,1]]:=a[i,3];
        end
      else
        begin
          b[a[i,1],a[i,2]]:=0;
          b[a[i,2],a[i,1]]:=0;
        end;
    for k:=1 to n do
      for i:=1 to n do
        if k<>i then
          for j:=1 to n do
            if (i<>j)and(j<>k) then
              if b[i,k]+b[k,j]<b[i,j] then
                b[i,j]:=b[i,k]+b[k,j];
    writeln(b[s1,s2]);
    close(input);close(output);
  end.