#include<bits/stdc++.h>

using namespace std;
typedef unsigned int uint;
typedef long long int ll;
typedef unsigned long long int ull;

#define debugv(v) printf("L%d %s => ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;
#define debugm(m) printf("L%d %s is..\n",__LINE__,#m);for(auto v:m){for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) printf("L%d %s is => ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;
#define debugaa(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[x][y]<<" ";}cout<<endl;}
#define ALL(v) (v).begin(),(v).end()
#define BIGINT 0x7FFFFFFF
#define E107 1000000007
void printbit(int u){if(u==0)cout<<0;else{int s=0,k=0;for(;0<u;u>>=1,k++)s=(s<<1)|(u&1);for(;0<k--;s>>=1)cout<<(s&1);}}

#define TIME chrono::system_clock::now()
#define MILLISEC(t) (chrono::duration_cast<chrono::milliseconds>(t).count())

template<typename T1,typename T2>
ostream& operator <<(ostream &o,const pair<T1,T2> p){o<<"("<<p.first<<":"<<p.second<<")";return o;}

vector<int> nonprime;
vector<int> primelist;

void gen_primelist(vector<int>& out, int high){
    int i,j;
    out.resize(high+1);
    out[0] = out[1] = 1;
    int sqh = (int)sqrt(high);
    for (i=2; i<=sqh; i++){
        if (out[i] == 0){
            for (j=i*i; j<=high; j+=i){ // i*i
                out[j] = 1;
            }
        }
    }
}

int width,height;
int m,n;

int memo[20000];
int memoused[20000];
int calc(int num,int pi=0){
    //printf("%d %d\n",num,pi);
    if (num == 0) return 1;
    
    if (memoused[num]) return memo[num];
    memoused[num] = 1;
    
    int res = 0,t;
    for (int i=pi;i<primelist.size();i++){
        if (primelist[i]>num) break;
        t = calc(num-primelist[i],i+1);
        if (t)
            res = max(res,t+1);
    }
    return memo[num] = res;
}

int main(){
    int i,j,k;
    int x,y,a,b;
    
    cin >> n;
    
    switch(n){
        case 1:
        case 4:
            cout << -1 << endl;
            break;
        case 2:
        case 3:
        case 5:
            cout << 1 << endl;
            break;
        default:
            gen_primelist(nonprime,n);
            primelist.reserve(2000);
            for (i=2;i<=n;i++){
                if (!nonprime[i])
                    primelist.push_back(i);
            }
            
            cout << (calc(n)-1) << endl;
    }
    
    
    return 0;
}