/***********Template Starts Here***********/

//#include <bits/stdc++.h>

#include <cstdio>

#include <cstring>

#include <cmath>

#include <algorithm>

#include <map>

#include <queue>

#include <stack>

#include <vector>

#include <deque>

#include <functional>

#include <string>

#include <iostream>

#include <cctype>

#include <set>

#include <climits>

#include <iomanip>

#include <cassert>

#include <sstream>

#define pb push_back

#define nl puts ("")

#define sp printf ( " " )

#define phl printf ( "hello\n" )

#define ff first

#define ss second

#define POPCOUNT __builtin_popcountll

#define RIGHTMOST __builtin_ctzll

#define LEFTMOST(x) (63-__builtin_clzll((x)))

#define MP make_pair

#define CLR(x,y) memset(x,y,sizeof(x))

#define UNIQUE(V) (V).erase(unique((V).begin(),(V).end()),(V).end())

#define MIN(a,b) ((a)<(b)?(a):(b))

#define MAX(a,b) ((a)>(b)?(a):(b))

#define NUMDIGIT(x,y) (((vlong)(log10((x))/log10((y))))+1)

#define SQ(x) ((x)*(x))

#define ABS(x) ((x)<0?-(x):(x))

#define FABS(x) ((x)+eps<0?-(x):(x))

#define ALL(x) (x).begin(),(x).end()

#define LCM(x,y) (((x)/gcd((x),(y)))*(y))

#define SZ(x) ((vlong)(x).size())

#define NORM(x) if(x>=mod)x-=mod;

#define MOD(x,y) (((x)*(y))%mod)

#define ODD(x) (((x)&1)==0?(0):(1))

using namespace std;

typedef long long vlong;

typedef unsigned long long uvlong;

typedef pair < vlong, vlong > pll;

typedef vector<pll> vll;

typedef vector<vlong> vl;

const vlong inf = 2147383647;

const double pi = 2 * acos ( 0.0 );

const double eps = 1e-9;

struct debugger{

template<typename T> debugger& operator , (const T& v){

cerr<<v<<" ";

return *this;

}

}dbg;

inline vlong gcd ( vlong a, vlong b ) {

a = ABS ( a ); b = ABS ( b );

while ( b ) { a = a % b; swap ( a, b ); } return a;

}

vlong ext_gcd ( vlong A, vlong B, vlong *X, vlong *Y ){

vlong x2, y2, x1, y1, x, y, r2, r1, q, r;

x2 = 1; y2 = 0;

x1 = 0; y1 = 1;

for (r2 = A, r1 = B; r1 != 0; r2 = r1, r1 = r, x2 = x1, y2 = y1, x1 = x, y1 = y ) {

q = r2 / r1;

r = r2 % r1;

x = x2 - (q * x1);

y = y2 - (q * y1);

}

*X = x2; *Y = y2;

return r2;

}

inline vlong modInv ( vlong a, vlong m ) {

vlong x, y;

ext_gcd( a, m, &x, &y );

x %= m;

if ( x < 0 ) x += m; //modInv is never negative

return x;

}

inline vlong power ( vlong a, vlong p ) {

vlong res = 1, x = a;

while ( p ) {

if ( p & 1 ) res = ( res * x );

x = ( x * x ); p >>= 1;

}

return res;

}

inline vlong bigmod ( vlong a, vlong p, vlong m ) {

vlong res = 1 % m, x = a % m;

while ( p ) {

if ( p & 1 ) res = ( res * x ) % m;

x = ( x * x ) % m; p >>= 1;

}

return res;

}

/***********Extended****************/

#define sc(x) scanf("%d",&x)

#define scl(x) scanf("%lld",&x)

#define scc(x,y) scanf("%d %d",&x,&y)

#define sccl(x,y) scanf("%lld %lld",&x,&y)

#define sccc(x,y,z) scanf("%d %d %d",&x,&y,&z)

#define scccl(x,y,z) scanf("%lld %lld %lld",&x,&y,&z)

#define prc(c) printf("Case %d: ",c)

#define prn(c) printf("Case %d:\n",c)

#define pr(c) printf("%d\n",c)

#define prl(c) printf("%lld\n",c)

#define FORL(x,y,z) for(int x = y ; x<z ; x++)

#define FORE(x,y,z) for(int x = y ; x<=z; x++)

#define ROFE(x,y,z) for(int x = y ; x>=z; x--)

#define lli long long int

//int dx[] = {-1,1,0,0};

//int dy[] = {0,0,-1,1};

/***********Template Ends Here***********/

/*

int flag[50005];

int prime[50005];

int ind = 0;

void sieve(){

flag[0] = 1;

flag[1] = 1;

for(int i=4;i<=50000;i+=2) flag[i]++;

prime[0] = 2;

ind = 1;

for(int i=3;i<=50000;i+=2){

if(!flag[i]){

prime[ind] = i;

ind++;

for(int j=i+i;j<=50000;j+=i)

flag[j]++;

}

}

// cout<<prime[0]<<endl;

// cout<<prime[1]<<endl;

// cout<<prime[2]<<endl;

}

*/

/********************DONE***************/

int main(){

int n;

cin>>n;

if(n%2==1){

int t = n/2;

cout<<t<<endl;

cout<<3;

for(int i=1;i<t;i++) {

cout<<" "<<2;

}

cout<<endl;

}

else{

int t = n/2;

cout<<t<<endl;

for(int i=0;i<t;i++) {

if(i==0) cout<<2;

else cout<<" "<<2;

}

cout<<endl;

}

}