{$R-}
var
  n,k,i,j,max,nom1 : longint;
  a,b,nom,g : array [1..50000] of longint;
begin
  assign(input,'elect.in'); reset(input);
  assign(output,'elect.out'); rewrite(output);
  readln(n,k);
  for i:=1 to n do readln(a[i],b[i]);
  max:=a[1];
  for i:=1 to k do
    begin
      max:=a[1]; nom1:=1;
      for j:=1 to n do
        if a[j]>max
          then begin
                 max:=a[j];
                 nom1:=j;
               end;
      a[nom1]:=0; nom[i]:=nom1;
    end;
  for i:=1 to k do
    g[i]:=b[nom[i]];
  max:=g[1];
  for i:=1 to k do
    if g[i]>max then begin max:=g[i]; nom1:=nom[i]; end;
  writeln(nom1);
  close(input);
  close(output);
end.