Store remaining numbers after sample() function

score = c(22,20,30,12,29,21,18,31,27,29,22,48,13,18,10,11,17,10,22,28,14,19,30,22,9)

x <- sample(score,size=13,replace=FALSE) 
y <- # I want y to store the numbers that were left behind after sample()

If I use the setdiff() function, it will remove all the duplicated number from the score list which is not what I'm looking for.

Can anybody give me some hints?