584D.cpp

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*/                              
#include<bits/stdc++.h>
using namespace std;
 
#define fastio ios_base::sync_with_stdio(0); cin.tie(0)
#define LL long long 
#define mod 1000000007 
#define all(v) v.begin(),v.end()
#define FOR(i, j, k) for (auto i=j ; i<k ; i++)
#define ROF(i, j, k) for (auto i=j ; i>=k ; i--) 
#define debug(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)
#define time__(d) for(long blockTime = 0; (blockTime == 0 ? (blockTime=clock()) != 0 : false); debug("%s time : %.4fs", d, (double)(clock() - blockTime) / CLOCKS_PER_SEC))

const long long INF = 1e18;
const long long MAX = 1e6+10;
bool prime[MAX]; 

void Si(){ 
    memset(prime, true, sizeof(prime));   
    for (int p=2; p*p<MAX; p++)     
        if (prime[p] == true)         
            for (int i=p*p; i<MAX; i += p) 
                    prime[i] = false; 
} 
int main(){
    fastio;
    int t=1;// cin>>t;
    Si();
    while(t--){
        int n; cin>>n;  
        int cnt = 0;
        for(int i = 2; i*i<=n ;i++) if(n%i==0) cnt++;
        if(cnt==0) {cout<<1<<"\n"<<n; return 0;}
        if(n==4) {cout<<2<<"\n"<<2<<" "<<2; return 0;}
        if(n==6) {cout<<2<<"\n"<<3<<" "<<3; return 0;}
        cout<<3<<"\n"<<3<<" ";
        n-=3;
        FOR(i,2,MAX) {
            if(prime[i] && (n-i > 0 && n-i<MAX && prime[n-i]) ) {cout<<i<<" "<<n-i;  break;}
            int s=n-i;
            bool sol =false;
            if(!prime[i]) continue;
            FOR(j,2,MAX) {
                if(s%j==0 && prime[j]) break;
                if(prime[j] &&  j*j>s) {cout<<i<<" "<<s; sol=true; break;}
            }
            if(sol) break;
        }
    }
}