uses math;
const
  fi='hirehp.inp';
  fo='hirehp.out';
  maxn=5*trunc(1e5);
  oo=trunc(1e18);
var
  tree : array[1..4*maxn] of int64;
  idleaf : array[1..maxn] of longint;
  i,j,n : longint;
  f : array[1..maxn] of int64;
  t,p : array[1..maxn] of longint;
procedure build(k,l,r : longint);
  var m : longint;
  begin
    if l = r then
      begin
        idleaf[l] := k;
        exit;
      end;
    m := (l+r) div 2;
    build(k*2,l,m);
    build(k*2+1,m+1,r);
  end;
procedure update(j: longint; x : int64);
  begin
    i := idleaf[j];
    while i > 0 do
      begin
        tree[i] := min(tree[i] , x);
        i := i div 2;
      end;
  end;
function get(k,l,r,i,j : longint) : int64;
  var m  :  longint;
      tg1,tg2 : int64;
  begin
    if (i>r) or (j<l) then exit(oo);
    if (i<=l) and (j>=r) then exit(tree[k]);
    m := (l+r) div 2;
    tg1 := get(k*2,l,m,i,j);
    tg2 := get(k*2+1,m+1,r,i,j);
    get := min(tg1,tg2);
  end;
procedure main;
var i : longint;
begin
//  assign(input,fi);reset(input);
//assign(output,fo);rewrite(output);
  read(n);
  for i := 1 to n do read(t[i] , p[i]);
  for i := 1 to 4*n do tree[i] := oo;
  build(1,1,n);
  update(t[1] , p[1]);
  f[1] := p[1];
  for i := 2 to n do
    begin
      f[i] := get(1,1,n,i-1,n) + p[i];
      update(t[i] , f[i]);
    end;
  writeln(get(1,1,n,n,n));
  //close(input);close(output);
end;
begin
  main;
end.

uses math; const fi='hirehp.inp'; fo='hirehp.out'; maxn=5*trunc(1e5); oo=trunc(1e18); var tree : array[1..4*maxn] of int64; idleaf : array[1..maxn] of longint; i,j,n : longint; f : array[1..maxn] of int64; t,p : array[1..maxn] of longint; procedure build(k,l,r : longint); var m : longint; begin if l = r then begin idleaf[l] := k; exit; end; m := (l+r) div 2; build(k*2,l,m); build(k*2+1,m+1,r); end; procedure update(j: longint; x : int64); begin i := idleaf[j]; while i > 0 do begin tree[i] := min(tree[i] , x); i := i div 2; end; end; function get(k,l,r,i,j : longint) : int64; var m : longint; tg1,tg2 : int64; begin if (i>r) or (j<l) then exit(oo); if (i<=l) and (j>=r) then exit(tree[k]); m := (l+r) div 2; tg1 := get(k*2,l,m,i,j); tg2 := get(k*2+1,m+1,r,i,j); get := min(tg1,tg2); end; procedure main; var i : longint; begin // assign(input,fi);reset(input); //assign(output,fo);rewrite(output); read(n); for i := 1 to n do read(t[i] , p[i]); for i := 1 to 4*n do tree[i] := oo; build(1,1,n); update(t[1] , p[1]); f[1] := p[1]; for i := 2 to n do begin f[i] := get(1,1,n,i-1,n) + p[i]; update(t[i] , f[i]); end; writeln(get(1,1,n,n,n)); //close(input);close(output); end; begin main; end.