def ascan; gets.split.map(&:to_i);end


str = gets.chomp

n = str.size

r = 0
while str.chars.sort != str.chars
    1.upto(n-1){|i|
        if str[i-1]>str[i]
            r += 1
            str[i-1],str[i] = str[i],str[i-1]
        end
    }
end

p r