#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

const int MAX=8001;
const int INF=1e9;
vector<int> prime;
bool isprime[MAX];
 
void sieve(){
	for(int i=3; i<MAX; i+=2){
		isprime[i]=1;
	}
	isprime[2]=1;
	prime.push_back(2);
	for(int i=3; i<MAX; i++){
		if(isprime[i]){
			prime.push_back(i);
			for(int j=2*i; j<MAX; j+=i){
				isprime[j]=0;
			}
		}
	}
	return;
}

int main()
{
	int n;
	cin>>n;
	sieve();
	int dp[20001][92];
  int sum[92];
  sum[0]=0;
  for(int i=1; i<92; i++){
    sum[i]=sum[i-1]+prime[i-1];
  }
  for(int i=2; i<=n; i++) fill(dp[i], dp[i]+92, INF);
	for(auto x:prime) dp[x][1]=x;
	for(int i=1; i<91; i++){
		for(int j=sum[i]; j<=n; j++){
			if(dp[j][i]==INF) continue;
			int k=upper_bound(prime.begin(), prime.end(), dp[j][i])-prime.begin();
          if(k==prime.size()) continue;
			for(int l=k; (l<prime.size() && j+prime[l]<=n); l++){
				dp[j+prime[l]][i+1]=min(dp[j+prime[l]][i+1], prime[l]);
			}
		}
	}
	for(int i=91; i>=1; i--){
		if(dp[n][i]<INF){
			cout<<i<<endl;
			return 0;
		}
    }
	cout<<-1<<endl;
	return 0;
}