a = gets.chomp.to_i
b = gets.chomp.to_i
c = gets.chomp.to_i

brothers = {}
brothers[a] = 'A'
brothers[b] = 'B'
brothers[c] = 'C'
#p brothers
brothers.sort{|(height1, name1), (height2, name2)|
    height2 <=> height1
}.map{|height, name|
    puts name
}