#include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <map>
using namespace std;

vector<int> sosuu;
int n;

int dp[2300][100000];

int solve(int i,int num){
    if(i == sosuu.size() && num != n) return -2 * sosuu.size();
    else if(num == n) return 0;
    
    if(num > n) return -2 * sosuu.size();
    
    if(dp[i][num] != 0) return dp[i][num];
    
    return dp[i][num] = max( solve(i+1,num+sosuu[i]) + 1, solve(i+1,num) );
    
}

int main(void){
    // Here your code !
    cin >> n;
    
    for(int i = 2; i <= n; i++){
        bool f = true;
        for(int j = 2; j <= sqrt(i); j++){
            if(i%j == 0){
                f = false;
                break;
            }
        }
        if(f) sosuu.push_back(i);
    }
    
    int res = solve(0,0);
    
    if(res >= 1){
        cout << res << endl;
    }else{
        cout << -1 << endl;
    }
    
}