local mmi, mma = math.min, math.max
n, m = io.read("*n", "*n")
t = {}
for i = 1, m do t[i] = 0 end
for rep = 1, n do
  s, a = io.read("*n", "*n")
  for i = m - s, 1, -1 do
    t[i + s] = mma(t[i + s], t[i] + a)
  end
  if s <= m then
    t[s] = mma(t[s], a)
  end
end
print(t[m])