A function asisgns to each element of a set, exactly one element of a related set. ΠΠΊΠΎ Π΄Π΅ΡΠΈΠ½ΠΈΡΠΈΠΎΠ½Π½Π°ΡΠ° ΠΎΠ±Π»Π°ΡΡ Π΅ Π΄Π΅ΠΊΠ°ΡΡΠΎΠ²ΠΎΡΠΎ ΠΏΡΠΎΠΈΠ·Π²Π΅Π΄Π΅Π½ΠΈΠ΅: