require 'set'
n,x,d=gets.split.map(&:to_i)

base = n*(n-1)/2

set = Set[]

(0..n).each{|nn|
  top = base - nn*(nn-1)/2
  bottom = base - nn*(n-1+n-nn)/2
  (bottom..top).each{|i|
    set.add(x*(n-nn-nn) + d*(i-base+i))
#    p set
  }
#  p [nn,top,bottom]
}
p set.size
#p set