Hello all, I have the sheet with the following data

12 1 01 6
18 1 01 10
12 1 01 6
11 5 09 3
12 1 10 1
12 2 01 12
12 1 01 2
11 5 09 5
11 5 11 23

The data on the last column is the count, I need to get the following
output

12 1 01 12 (sum of row 1 & 3)
18 1 01 10
11 5 09 8 (sum of row 4 & 8)
12 1 10 1
12 2 01 12
12 1 01 2
11 5 11 23

This is what the above results is - data from row1 for colA, colB &
colC is compared with the data with row2: ColA, ColB, ColC, and if
they are same then the data from ColD is summed up. I was trying to do
it through SumProduct, but could not achieve what I was trying to do.
So in the above example row 1 & 3 are same when u compare ColA, ColB &
ColC, so I add up the values in column D. Basically I need unique
values to be selected from ColA, ColB & colC and if there are more
than one row with the same value I need to sum the data in ColD. Hope
I have not confused with too many things. I need this to be done as
part of the macro That I'm creating

Thankyou for any help. Thanks in advance.