#include "ec.h"

___START___

INT n _dt m _then
in_ n _i_ m _then
if k_ k_ m _more_ n _k _bor_ k_ n _less_ 0 _k _bor_ k_ m _less_ 0 _k _k ket_
    out_ 0 _o_ _br _then
    return 0 _then
_ket
if k_ m _more_ n _div_ 2 _k ket_
    m _get_ k_ n _sub_ m _k _then
_ket
//out_ n _o_ nbsp_ _o_ m _o_ _br _then
LINT fz _get_ 1 _then
LINT fm _get_ 1 _then
for k_ _then m _more_ 0 _then n _seltt _dt m _seltt _k ket_
    fm _tim__get_ m _then
    fz _tim__get_ n _then
_ket
out_ fz _div_ fm _then

___OVER___

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