var
  i,j,k,a,b,n,m,t:longint;
  map:array[1..300,1..300]of longint;
function min(a,b:longint):longint;
begin
  if a<b then min:=a else min:=b;
end;
function max(a,b:longint):longint;
begin
  if a>b then max:=a else max:=b;
end;
begin
  assign(input,'hurdles.in');
  reset(input);
  assign(output,'hurdles.out');
  rewrite(output);
  read(n,m,t);
  for i:=1 to n do
    for j:=1 to n do
      map[i,j]:=maxlongint;
  for i:=1 to m do
    read(a,b,map[a,b]);
  for k:=1 to n do
    for i:=1 to n do
      for j:=1 to n do
        map[i,j]:=min(map[i,j],max(map[i,k],map[k,j]));
  for i:=1 to t do begin
    read(a,b);
    if map[a,b]=maxlongint then writeln(-1) else writeln(map[a,b]);
  end;
  close(input);
  close(output);
end.