import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    static int[] primes;
    static int[] sums;
    static int[][] dp;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        boolean[] isNotPrimes = new boolean[n + 1];
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 2; i <= n; i++) {
            if (!isNotPrimes[i]) {
                for (int j = 2; j * i <= n; j++) {
                    isNotPrimes[j * i] = true;
                }
                list.add(i);
            }
        }
        primes = new int[list.size()];
        sums = new int[list.size()];
        for (int i = 0; i < list.size(); i++) {
            primes[i] = list.get(i);
            if (i > 0) {
                sums[i] = sums[i - 1] + primes[i];
            }
        }
        dp = new int[list.size()][n + 1];
        for (int[] arr : dp) {
            Arrays.fill(arr, Integer.MAX_VALUE);
        }
        int ans = dfw(list.size() - 1, n);
        if (ans < 0) {
            System.out.println(-1);
        } else {
            System.out.println(ans);
        }
    }
    
    static int dfw(int idx, int v) {
        if (v == 0) {
            return 0;
        }
        if (idx < 0 || v < 0 || sums[idx] < v) {
            return Integer.MIN_VALUE;
        }
        if (dp[idx][v] == Integer.MAX_VALUE) {
            dp[idx][v] = Math.max(dfw(idx - 1, v), dfw(idx - 1, v - primes[idx]) + 1);
        }
        return dp[idx][v];
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}