program bestspot;
var f:array[1..500,1..500]of longint;
    b:array[1..500]of integer;
    t,k,m,n,i,j,x,y,p,min,an:longint;
begin
assign(input,'bestspot.in');
reset(input);
assign(output,'bestspot.out');
rewrite(output);
readln(n,p,m);
for t:=1 to p do
  begin
    readln(i);
    b[i]:=1;
  end;
fillchar(f,sizeof(f),1);
for t:=1 to m do
  begin
    read(x,y);
    readln(f[x,y]);
    f[y,x]:=f[x,y];
  end;
for i:=1 to n do
  for t:=1 to n do
    for k:=1 to n do
      if (f[t,i]<maxlongint)and(f[i,k]<maxlongint)and((f[t,i]+f[i,k]<f[t,k])) then
        f[t,k]:=f[t,i]+f[i,k];
for t:=1 to n do
  begin
    j:=0;
    for k:=1 to n do
      if (b[k]=1)and(t<>k) then j:=j+f[t,k];
    if (j<min)or(min=0) then
      begin
        min:=j;
        an:=t;
      end;
  end;
writeln(an);
close(output);
end.