#include <stdio.h>
int dp[2262][20001];
int furui[200001];
int primes[2262];
void prime() {
	int i, j;
	for (i = 0; i < 200001; i ++) furui[i] = 1;
	furui[0] = 0; furui[1] = 0;
	for (i = 2; i < 1001; i ++) {
		if (furui[i] == 1) {
			for (j = i * i; j < 20001; j += i) {
				furui[j] = 0;
			}
		}
	}
	int n = 0;
	for(i = 0; i < 20001; i ++) if(furui[i] == 1) primes[n ++] = i;
}
int max(int a, int b) {
	if(a > b) return a;
	return b;
}
void solve() {
	int i, p, m;
	for (i = 0; i < 2262; i ++) for (m = 0; m < 20001; m ++) dp[i][m] = -1;
	for (i = 0; i < 2262; i ++) dp[i][primes[i]] = 1;
	for (i = 1; i < 2262; i ++) {
		for (m = 0; m < 20001; m ++) {
			if(m - primes[i] > 0  && dp[i - 1][m - primes[i]] != -1) {
				dp[i][m] = max(dp[i][m], max(dp[i - 1][m], dp[i - 1][m - primes[i]] + 1));
			} else {
				dp[i][m] = max(dp[i][m], dp[i - 1][m]);
			}
		}
	}
}
int main() {
	int n;
	prime();
	solve();
	scanf("%d", &n);
	printf("%d\n", dp[2262 - 1][n]);
}