#include <stdio.h>
#include <stdlib.h>
#include <math.h>

short p[1000];
short pNum;

void makePrimeList(short n);

int main(void)
{
	short n,i,j;
	scanf("%hd",&n);

	makePrimeList(n+100);
	
	j=0;
	for (i=n-100;i<=n+100;i++) {
		for (;j<pNum;j++) {
			if (p[j] < i) continue;
			if (p[j] > i && i!=1) {
				printf("%hd\n",i);
				return 0;
			}
			break;
		}
	}

	return 0;
}

// return number of prime
void makePrimeList(short n)
{
	short i,j,*tmpP;
	tmpP = (short *)malloc(sizeof(short) * n);
	tmpP[0] = 1;
	for (i=1;i<n;i++) tmpP[i] = 0;

	pNum = 0;
	for (i=2;i<=sqrt(n);i++) {
		if (tmpP[i-1]==1) continue;
		
		p[pNum] = i;
		pNum++;
		for (j=i;j<=n;j+=i) {
			tmpP[j-1] = 1;
		}
	}

	for (i=(int)sqrt(n);i<=n;i++) {
		if (tmpP[i-1]==1) continue;

		p[pNum] = i;
		pNum++;
	}

	return;
}