lib C
  fun strtoll(s : UInt8*, p : UInt8**, b : Int32) : Int64
end

class String
  def to_i64
    C.strtoll(self, nil, 10)
  end
end

# require "utility/CulSum"
# description : 累積和
class CulSum(T)
  def initialize(a : Array(T))
    @n = a.size
    @s = Array(T).new(@n + 1, T.zero)
    @n.times do |i|
      @s[i + 1] = @s[i] + a[i]
    end
  end

  def initialize(@n : Int32, &f : Int32 -> T)
    @s = Array(T).new(@n + 1, T.zero)
    @n.times do |i|
      @s[i + 1] = @s[i] + yield(i)
    end
  end

  def initialize(a, &f)
    @n = a.size
    @s = Array(T).new(@n + 1, T.zero)
    @n.times do |i|
      @s[i + 1] = @s[i] + yield(a[i])
    end
  end

  def [](left : Int32, count : Int32)
    @s[left + count] - @s[left]
  end

  def [](range : Range)
    self[*Indexable.range_to_index_and_count(range, @n) || raise IndexError.new]
  end

  def to_a
    (0...@n).map { |i| self[i..i] }
  end
end


n, q = read_line.split.map(&.to_i)
s = read_line
sum = ('a'..'z').map { |c|
  CulSum(Int32).new(s) { |c2| c == c2 ? 1 : 0 }
}
q.times do
  l, r, x = read_line.split.map(&.to_i)
  l -= 1
  cnt = (0...26).map { |i| sum[i][l...r] }
  cnt_sum = 0
  puts 'a' + cnt.each_with_index.find { |c, i|
    cnt_sum += c
    cnt_sum >= x
  }.not_nil![1]
end