combining two variables together, including NA

I am trying to combine two binary variables together as a single variable, so if there is a 0 in one and a 1 in the other it would be a 1. This contains NAs. Example

a <- c("A", NA, 0)
b <- c("B",0,  1)
c <- c("C", 0, 0)
d <- c("D", 0, 1)
e <- c("E", NA, NA)
aa<- rbind(a,b,c,d,e)
aa <- as.data.frame(aa) 

I would like to code this to give me:

a <- c("A", NA, 0, 0)
b <- c("B",0,  1, 1)
c <- c("C", 0, 0, 0)
d <- c("D", 0, 1, 1)
e <- c("E", NA, NA, NA)
bb<- rbind(a,b,c,d, e)
bb <- as.data.frame(bb) 

I think this is an easy fix.

>Solution :

Use base R, use rowSums to create the V4 column by comparing the columns of interest with 1 and then replace the values in ‘V4’ to NA where there are all NAs in a row in columns 2 and 3

aa$V4 <- rowSums(aa[-1] == 1,  na.rm = TRUE)
aa$V4[rowSums(is.na(aa[2:3])) == 2] <- NA

-output

> aa
  V1   V2   V3 V4
a  A <NA>    0  0
b  B    0    1  1
c  C    0    0  0
d  D    0    1  1
e  E <NA> <NA> NA