(not) know the first thing about
Meaning: to know nothing about something, not to have any knowledge about
Example: I don’t know the first thing about nuclear physics.
Π‘Π΅ΡΠΈΠ°Π»Ρ ΠΈ ΡΠΈΠ»ΡΠΌΡ Π½Π° Π°Π½Π³Π»ΠΈΠΉΡΠΊΠΎΠΌ Ρ ΡΡΠ±ΡΠΈΡΡΠ°ΠΌΠΈ. +1 ΠΠ΅ΡΡΡ Π² ΠΏΠΎΠ΄Π°ΡΠΎΠΊ π
Example: I don’t know the first thing about nuclear physics.