program hurdles(input,output);
var
 map:array[1..300,1..300]of longint;
 n,m,t,i,j,k,x,y:longint;
function max(a,b:longint):longint;
begin
 if a>b then exit(a) else exit(b);
end;
begin
 assign(input,'hurdles.in');assign(output,'hurdles.out');
 reset(input);rewrite(output);
 readln(n,m,t);
 fillchar(map,sizeof(map),0);
 for i:=1 to m do readln(x,y,map[x,y]);
 for k:=1 to n do
  for i:=1 to n do
   for j:=1 to n do
    if (map[i,k]>0)and(map[k,j]>0)and((max(map[i,k],map[k,j])<map[i,j])
    or (map[i,j]=0))then map[i,j]:=max(map[i,k],map[k,j]);
 for i:=1 to t do begin
  readln(x,y);
  if map[x,y]=0 then writeln(-1) else writeln(map[x,y]);
 end;
 close(input);close(output);
end.