Place of birth in Russia, possibly Ukraine region of Volhynia?

[Mavals]

I am helping my husband's cousin's wife with her side of her family tree

Her father was born in Russia in 1902 and the extract below is from USA/ Canada border crossing information. The top line gives mother's place of birth and the lower line , the children's place of birth.

I rather suspect the place has been written phonetically and we have tried comparing with other words written by the immigration officer with no luck so far. If anyone has any ideas or suggestions for a place of birth we would be very grateful.

[Spidermonkey]

Kostopol in the Ukraine for the children?

[Mavals]

Thank very much, we checked that out and it triggered some memories of stories she had been told by her uncles. She is thrilled with what we have been able to find out.