#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <cassert>
using namespace std;
typedef long long ll;
#define ss second
#define ff first
#define all(X) X.begin(), X.end()
#define rall(X) X.rbegin(), X.rend()
#define cinall(X) for(auto &i:X)cin >> i
#define printall(X) for(auto &i:X)cout << i
#define printFromTo(cont, i, j, ch) for(int _ = i; _ <= j; _++)cout << cont[_] << ch
#define readFromTo(cont, i, j) for(int _ = i; _ <= j; _++)cin >> cont[_]
#define fillFromTo(cont, i, j, x) for(int _ = i; _ <= j; _++)cont[_] = x;
#define pb push_back
#define MAKE_UNIQUE_KEEP_ORDER(vec) do { \
unordered_set<decltype((vec).front())> seen; \
(vec).erase(remove_if((vec).begin(), (vec).end(), [&](auto &val) { \
if (seen.count(val)) return true; \
seen.insert(val); \
return false; \
}), (vec).end()); \
} while(0)
#define UNIQUE_SORT(vec) do { \
sort((vec).begin(), (vec).end()); \
(vec).erase(unique((vec).begin(), (vec).end()), (vec).end()); \
} while(0)
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define MIN(v) *min_element(all(v))
#define MAX(v) *max_element(all(v))
#define LB(c, x) (lower_bound((c).begin(), (c).end(), (x)) - (c).begin())
#define UB(c, x) (upper_bound((c).begin(), (c).end(), (x)) - (c).begin())
const int N = 2e5 + 5;
const int LOG = 30;
const long long INFLL = 1e18;
const int INF = 1e9;
const long double epsilon = 0.000001;
const long long mod = 998244353;
constexpr ll TEN[] = {
1LL,
10LL,
100LL,
1000LL,
10000LL,
100000LL,
1000000LL,
10000000LL,
100000000LL,
1000000000LL,
10000000000LL,
100000000000LL,
1000000000000LL,
10000000000000LL,
100000000000000LL,
1000000000000000LL,
10000000000000000LL,
100000000000000000LL,
1000000000000000000LL,
};
long long binPowByMod(long long x, long long power, long long modx) {
long long res = 1;
long long base = x % modx;
while (power > 0) {
if (power & 1) res = (res * base) % modx;
base = (base * base) % modx;
power >>= 1;
}
return res;
}
void set_IO(string str = "")
{
if (!str.empty()) {
freopen((str + ".in").c_str(), "r", stdin);
freopen((str + ".out").c_str(), "w", stdout);
}
}
bool prime(ll x)
{
if (x < 2)return false;
for (ll i = 2; i * i <= x; i++)
{
if (x % i == 0)return false;
}
return true;
}
bool f = false;
map<ll, bool>vis;
vector<ll>ans;
ll a, b;
void dfs(ll node)
{
if (f)return;
ans.push_back(node);
vis[node] = true;
if (node == b)
{
cout << ans.size() << endl;
for (auto i : ans)
cout << i << " ";
f = true;
return;
}
if (prime(node + 2) && !vis[node + 2])dfs(node + 2);
if (f)return;
if (prime(node - 2) && !vis[node - 2])dfs(node - 2);
if (f)return;
if (prime(node - 2) && !vis[2])dfs(2);
if (prime(b - node) && !vis[b])dfs(b);
if (f)return;
if (prime(b - node + 2) && !vis[b - 2])dfs(b - 2);
if (f)return;
if (prime(b - node - 2) && !vis[b + 2])dfs(b + 2);
ans.pop_back();
}
void solve()
{
ll a, b;
cin >> a >> b;
dfs(a);
if (!f)cout << -1 << endl;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t = 1;
//cin >> t;
while (t--) {
solve();
cout << endl;
}
return 0;
}
