Sum last 3 non zeros in a row

Here I got 1 table where i got the following
1 5 4 7 8 3 0 7 0 8 0 2

I want to sum only the last 3 values from right to left ignoring the zeros, example it will sum 17.

Each of the numbers are in a cell.

Examples:
1 3 5 7 8 0 2 7 0 8 0 2 = 17
2 5 0 2 0 0 5 0 0 2 1 4 = 7
0 0 0 2 0 0 0 4 0 0 0 0 = 6 since there is only 2 values
2 0 0 0 0 0 0 0 0 0 0 0 = 2 since there is only 1 value
0 0 0 0 0 0 0 0 0 0 0 0 = 0 since there is no value

External resources

• forum.knime.com/t/sum-last-3-non-zeros-in-a-row/43658