for each array of int, create a new int array with the difference between each value continue adding int arrays until all values are 0 then add up the last value of the lowest array to the last value of the array above and add that value to the array above return the summ of all added last values.

for each array of int, create a new int array with the difference between each value continue adding int arrays until all values are 0 then add to the left the value that equals the leftmost value below plus the leftmost value on current line return the summ of all added last values (row 0).