#include <bits/stdc++.h>
using namespace std;
const int N = 100;
long long a , b;
vector<long long> primes;
bool isPrime(long long x) {
if (x < 2) {
return false;
}
for (long long i = 2; i <= sqrt(x); i++) {
if (x % i == 0) {
return false;
}
}
return true;
}
vector<vector<int> > g(N , vector<int>());
vector<bool> used(N , false);
vector<long long> ans;
void dfs(int v) {
used[v] = true;
if (primes[v] == b) {
cout << (int)ans.size() << '\n';
for (long long cur : ans) {
cout << cur << " ";
}
cout << '\n';
exit(0);
}
for (int to : g[v]) {
if (!used[to]) {
ans.push_back(primes[to]);
dfs(to);
ans.pop_back();
}
}
}
int main() {
ios_base :: sync_with_stdio(0);
cin.tie(0) , cout.tie(0);
cin >> a >> b;
for (long long i = a - 2; i <= a + 2; i++) {
if (isPrime(i)) {
primes.push_back(i);
}
}
for (long long i = b - 2; i <= b + 2; i++) {
if (isPrime(i)) {
primes.push_back(i);
}
}
primes.push_back(2);
sort(primes.begin() , primes.end());
primes.erase(unique(primes.begin() , primes.end()) , primes.end());
for (int i = 0; i < (int)primes.size(); i++) {
for (int j = i + 1; j < (int)primes.size(); j++) {
if (isPrime(primes[j] - primes[i])) {
g[i].push_back(j);
g[j].push_back(i);
}
}
}
for (int i = 0; i < (int)primes.size(); i++) {
if (primes[i] == a) {
ans.push_back(a);
dfs(i);
break;
}
}
cout << -1 << '\n';
return 0;
}
