Calculate number of days between 2 dates

cell H1964 is date (cell format ddd, dd-mmm-yyyy)
cell K1964 is date & time (cell format ddd, dd-mmm-yyyy h:mm AM/PM)

cell H1964 = 4-Sep-2019
cell K1964 = 4-Sep-2019 1:00 AM

this formula gives me result -1 (I want result 0)
=IFERROR(IF(ISBLANK($H1964),"",INT($H1964-K1964)),"")

if I change time in cell K1964 to 12:00 AM, I get result 0,
which is what I desire

You are calculation numbers of days which means it is zero. From 12 AM to 1 AM is zero only

That works...thanks a lot