#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
#define pb push_back
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
bool prime(int x){
if(x <= 1) return false;
for(int i = 2; i * i <= x; i++){
if(x % i == 0) return false;
}
return true;
}
void solve(){
int a,b;
cin >> a >> b;
if(prime(abs(a-b))){
cout << "2\n" << a << ' ' << b << endl;
return;
}
if(prime(a - 2) && prime(b - 2)){
cout << a << ' ' << 2 << ' ' << b << endl;
return;
}
if(prime(a-2) && prime(abs(a-2 - b))){
cout << "3\n" << a << ' ' << a - 2 << ' ' << b << endl;
}
else if(prime(a+2) && prime(abs(a+2 - b))){
cout << "3\n" << a << ' ' << a + 2 << ' ' << b << endl;
}
else if(prime(b-2) && prime(abs(b-2 - a))){
cout << "3\n" << a << ' ' << b - 2 << ' ' << b << endl;
}
else if(prime(b+2) && prime(abs(b+2 - a))){
cout << "3\n" << a << ' ' << b + 2 << ' ' << b << endl;
}
else cout << -1 << endl;
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
while(t--)
solve();
return 0;
}
