Flip numbers on a finite interval with known bounds

gistfile1.txt

# 'Flip' numbers on a number interval

# my_nums:   1      2                    5                                  10
#            1
# interval:  1 ---- 2 ---- 3 ---- 4 ---- 5 ---- 6 ---- 7 ---- 8 ---- 9 ---- 10


# Flipped:
# newnums:   1                                  6                    9      10
#                                                                           10
# interval:  1 ---- 2 ---- 3 ---- 4 ---- 5 ---- 6 ---- 7 ---- 8 ---- 9 ---- 10

my_nums <- c(1, 1, 2, 5, 10)
start_num <- 1
end_num <- 10

-my_nums + start_num + end_num