cud c:\c\cod
 A, B
[A:= II(0)
 B:= II(0)
IOu(0, A+B) CLf(0)
IOu(0, A-B) CLf(0)
IOu(0, A*B) CLf(0)
IOu(0, AB) CLf(0)        \uc  z
IOu(0, (0)) CLf(0)     \'  c f  (A)
]