#include <bits/stdc++.h>
#define PN 2270

using namespace std;

int N, PC = 0;
int prime[PN] = {0};
bool used[PN] = {false};
int dp[20001] = {0};
int result = 0;

void rec(int count = 0, int sum = 0){
    
    if(sum > N) return;
    if(sum == N){
        if(result < count) result = count;
        return;
    }
    
    if(dp[sum] != 0 && dp[sum] >= count) return;
    dp[sum] = count;
    
    int i;
    for(i = 0; i < PC; ++i){
        if(!used[i]){
            used[i] = true;
            rec(count + 1, sum + prime[i]);
            used[i] = false;
        }
    }
    
    return;
}

int main(void){
    
    cin >> N;
    
    int i, j, k;
    
    prime[PC++] = 2;
    for(i = 3; i <= N; i += 2){
		k = 0;
		for(j = 3; j <= sqrt(i); j += 2){
			if(i % j == 0){
				k = 1;
				break;
			}
		}
		if(k == 0) prime[PC++] = i;
	}
    
    rec();
    
    if(result) cout << result << endl;
    else cout << -1 << endl;
    
    return 0;
}