n = read_line.to_i
ab = Array.new(n) {
  {Int64, Int64}.from read_line.split.map(&.to_i64)
}.sort_by { |a, b| a + b }

dp = [nil.as(Int64?)] * -~n
dp[0] = 0
ab.each do |a, b|
  dp2 = dp.dup
  (0...n).each do |i|
    if (val = dp[i]) && val <= b
      dp2[i + 1] = val + a
    end
  end
  dp = dp2
end
puts dp.rindex(&.itself)