const mx=50001;
type vct=array[-1..100000] of longint;

var f,t:text;
    i,n,dx,dy,dr,m,sm,e,s:longint;
    x,y,v,a:vct;
    csd,cst,css:array[-1..100000] of int64;

procedure calcul(d:longint);
begin
  sm:=maxlongint;
  s:=0;
  e:=0;
  for i:=1 to n do
    inc(v[a[i]]);
  for i:=mx downto 1 do
    csd[i]:=csd[i+1]+v[i+1];
  for i:=0 to mx-d do
    css[i]:=css[i-1]+v[i];
  for i:=mx downto 1 do
    cst[i]:=cst[i+1]+csd[i+1]+v[i+1];
  for i:=0 to mx-d do
    begin
      s:=e+cst[i+d];
      e:=e+css[i];
      if s<sm then
        sm:=s;
    end;
  for i:=0 to mx do
    v[i]:=0;
end;





begin
  assign(f,'tribute.in');
  reset(f);
  assign(t,'tribute.out');
  rewrite(t);
  read(f,n,dx,dy);
  for i:=1 to n do
    read(f,x[i],y[i]);
  a:=x;
  calcul(dx);
  m:=sm;
  a:=y;
  calcul(dy);
  writeln(t,sm+m);
  close(f);
  close(t);
end.