#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<bool>all(n+1,true);
    all[0]=all[1]=false;
	for(int i = 2; i <= sqrt(n); i++){
		if(all[i]){
			for(int j = 0; i * (j + 2) <= n; j++)all[i *(j + 2)] = false;
		}
	}
    vector<int>prime{0};
	for(int i = 0; i <= n; i++){
		if(all[i])prime.push_back(i);
	}

    int prime_size=(int)prime.size();

    vector<vector<int>>dp(prime_size+1, vector<int>(n+1, -1));
    
    // for(int i=1;i<prime_size;++i)dp[i][prime[i]]=1;
    for(int i=1;i<prime_size;++i){
        dp[i][prime[i]]=max(1,dp[i][prime[i]]);
        for(int j=0;j<=n;++j){
            if(dp[i][j]!=-1){
                dp[i+1][j]=dp[i][j];
                if(j+prime[i+1]<=n)dp[i+1][j+prime[i+1]]=dp[i][j]+1;
            }
        }
    }

    cout << dp[prime_size][n] << endl;

    return 0;
}