How to deal with NaN values in R

Question

Due of my inexperience with programming and newness to R, my query and shoddy code are both newbie mistakes.

I was given a task in which I had to construct Fibonacci sequence numbers that were less than 4,000,000 using a while loop (the Fibonacci sequence is characterised by the fact that every number after the first two is the sum of the two preceding ones).

The total of the even integers in the created sequence had to then be calculated.

My response was successful, however I don't think the code was written very effectively. What might I have done differently?

If (x == 0 & y == 1), then > x - 0 > y - 1 > z - 0 While (x 4000000), cat(x), cat(y), cat(" ")