d, g = io.read("*n", "*n")
g = g / 100
psum = 0
p, c = {}, {}
for i = 1, d do
  p[i], c[i] = io.read("*n", "*n")
  c[i], psum = c[i] / 100, psum + p[i]
end
t = {}
currentmax = 0
ignoremax = psum + 1
for i = 0, psum do t[i] = 0 end

for i_d = 1, d do
  searchmax = currentmax + p[i_d]
  for summed_count = searchmax, 0, -1 do
    i_count_min = math.max(0, summed_count - currentmax)
    i_count_max = math.min(summed_count, p[i_d])
    for i_count = i_count_min, i_count_max do
      i_score = i_count * i_d
      if(i_count == p[i_d]) then i_score = i_score + c[i_d] end
      t[summed_count] = math.max(t[summed_count], t[summed_count - i_count] + i_score)
    end
  end
  currentmax = searchmax
end
for i = 1, psum do
  if(g <= t[i]) then print(i) break end
end
