//By BLADEVIL

var

    n                       :longint;

    i                       :longint;

    x, y                    :longint;

    t, tot                  :longint;

    key, s, left, right     :array[..] of longint;

    ft                      :longint;

    a, b                    :longint;

    ans                     :longint;

procedure right_rotate(var t:longint);

var

    k                       :longint;

begin

    k:=left[t];

    left[t]:=right[k];

    right[k]:=t;

    s[k]:=s[t];

    s[t]:=s[left[t]]+s[right[t]]+;

    t:=k;

end;

procedure left_rotate(var t:longint);

var

    k                       :longint;

begin

    k:=right[t];

    right[t]:=left[k];

    left[k]:=t;

    s[k]:=s[t];

    s[t]:=s[left[t]]+s[right[t]]+;

    t:=k;

end;

procedure maintain(var t:longint;flag:boolean);

begin

    if not flag then

        if s[left[left[t]]]>s[right[t]] then

            right_rotate(t) else

            if s[right[left[t]]]>s[right[t]] then

            begin

                left_rotate(left[t]);

                right_rotate(t);

            end else exit

    else

        if s[right[right[t]]]>s[left[t]] then

            left_rotate(t) else

            if s[left[right[t]]]>s[left[t]] then

            begin

                right_rotate(right[t]);

                left_rotate(t);

            end else exit;

    maintain(left[t],false);

    maintain(right[t],true);

    maintain(t,true);

    maintain(t,false);

end;

procedure insert(var t:longint; v:longint);

begin

    if t= then

    begin

        inc(tot);

        t:=tot;

        key[t]:=v;

        s[t]:=;

        left[t]:=;

        right[t]:=;

    end else

    begin

        inc(s[t]);

        if v<key[t] then insert(left[t],v) else insert(right[t],v);

        maintain(t,v>=key[t]);

    end;

end;

function delete(var t:longint; v:longint):longint;

begin

    dec(s[t]);

    if (v=key[t]) or (v<key[t]) and (left[t]=) or (v>key[t]) and (right[t]=) then

    begin

        delete:=key[t];

        if (left[t]=) or (right[t]=) then

            t:=left[t]+right[t] else

            key[t]:=delete(left[t],key[t]+);

    end else

        if v<key[t] then delete:=delete(left[t],v) else delete:=delete(right[t],v);

end;

function pre(var t:longint; v:longint):longint;

begin

    if t= then exit(-);

    if v<key[t] then pre:=pre(left[t],v) else

    begin

        pre:=pre(right[t],v);

        if pre=- then pre:=key[t];

    end;

end;

function succ(var t:longint; v:longint):longint;

begin

    if t= then exit(-);

    if key[t]<=v then succ:=succ(right[t],v) else

    begin

        succ:=succ(left[t],v);

        if succ=- then succ:=key[t];

    end;

end;

begin

    read(n);

    ans:=;

    t:=; tot:=; s[t]:=;

    for i:= to n do

    begin

        read(x,y);

        if x=ft then insert(t,y) else

            if s[t]= then

            begin

                ft:=x;

                insert(t,y);

            end else

            begin

                a:=pre(t,y); b:=succ(t,y);

                if a=- then a:=-maxlongint div ;

                if b=- then b:=maxlongint div ;

                if abs(b-y)<abs(y-a) then

                begin

                    ans:=(ans+abs(b-y)) mod ;

                    b:=delete(t,b);

                end else

                begin

                    ans:=(ans+abs(y-a)) mod ;

                    a:=delete(t,a);

                end;

            end;

    end;

    writeln(ans);

end.