local mfl, mce = math.floor, math.ceil
local n, k = io.read("*n", "*n", "*l")
local s = io.read()
local t = {}
for i = 1, n do
  t[i] = s:byte(i) - 48
end

local function sub(x)
  local rem = x % n
  local a = mfl(x / n)
  local z = 0
  for i = 1, n do
    if 0 < rem and i <= rem then
      z = z + (a + 1) * t[i]
    else
      z = z + a * t[i]
    end
  end
  return z
end

local function solve(x)
  local add = 0
  local px = x
  local z = sub(px)
  while add ~= z do
    if 1000 < add then return true end
    add = z
    px = x + z
    z = sub(px)
  end
  return k <= x + add
end

local min, max = 0, k
while 1 < max - min do
  local mid = mfl((min + max) / 2)
  if solve(mid) then
    max = mid
  else
    min = mid
  end
end
print(max)