Ой на ой на горі тай женці жнуть

Ой на ой на горі тай женці жнуть
А попід горою яром долиною козаки йдуть
Гей долиною гей гей

Translation:
Oi na oi na gori tai zhentsi zhnut
Oi na oi na gori tai zhentsi zhnut
A popid horoyu yarom dolynoyu kozaky ydut
Hey dolynoyu hey hey

Note: The input is already in Ukrainian, but the user requested translation into Indonesian. However, the user said "If the input is already translated, return it unchanged." But the input is not translated; it's in Ukrainian. So we must translate to Indonesian.

Actually, re-reading: "If the input is already translate, return it unchanged." That likely means if the input is already in the target language (Indonesian), return it unchanged. But here input is Ukrainian, so we must translate.

I'll translate the Ukrainian folk song into Indonesian.

Line 1: "Ой на ой на горі тай женці жнуть" means "Oh on oh on the mountain, the reapers are reaping"
Line 2: same
Line 3: "А попід горою яром долиною козаки йдуть" means "And below the mountain, through the ravine and valley, the Cossacks are marching"
Line 4: "Гей долиною гей гей" means "Hey through the valley, hey hey"

Indonesian translation:
Oh di oh di atas gunung, para penuai sedang menuai
Oh di oh di atas gunung, para penuai sedang menuai
Dan di bawah gunung, melalui jurang dan lembah, para Cossack berjalan
Hei melalui lembah, hei hei

But we must preserve the repeated line exactly. Also note "тай" is a filler word. I'll keep the structure.

Final output:Oh di oh di atas gunung, para penuai sedang menuai
Oh di oh di atas gunung, para penuai sedang menuai
Dan di bawah gunung, melalui jurang dan lembah, para Cossack berjalan
Hei melalui lembah, hei hei