import strutils
proc prime(n: int): seq[int] =
  let gaps: array[-2..8, int] = [1, 2, 2, 4, 2, 4, 2, 4, 6, 2, 6]
  var
    m: int = n
    p: int = 2
    ind: int = -2
    ret: seq[int]
  while p * p <= m:
    while m mod p == 0:
      ret.add(p)
      m = m div p
    p += gaps[ind mod 9]
    ind.inc
  if m > 1:
    ret.add(m)
  return ret
let n: int = stdin.readline.parseInt
var ans: int
for i in (n - 100)..(n + 100):
  if prime(i).len > 1:
    ans = i
    break
echo ans