# import sys; input = sys.stdin.buffer.readline
# sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

num = 2 * 10 ** 3 + 1 #適当に値を入れる
L = [1 for i in range(num)]; L[0] = 0; L[1] = 0
plist = [1]
for i in range(num):
	if L[i] == 1:
		plist.append(i); c = 2
		while i * c <= num - 1:
			L[i * c] = 0; c += 1

#処理内容
def main():
	N = int(input())
	for i in range(N - 100, N + 101):
		if not i in plist:
			print(i)
			return



if __name__ == '__main__':
	main()