class CountUpTrees
    attr_reader :s

    def initialize(s: "")
        @s = s
    end

    def cause
        begin
            @s = gets.chomp
        rescue
            
        end
    end

    def countuptrees(target, str)
        str_hash = {}
        str.split("").uniq.each do |c|
            str_hash[c] = str.count(c)
        end
        cnt_ary = str_hash.each.map do |c, cnt|
            target.count(c) / cnt
        end
        cnt_ary.min
    end

    def result
        puts countuptrees(@s, "tree")
    end

    def run
        cause
        result
    end
end

if $0 == __FILE__
    CountUpTrees.new.run
end