#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 100;
int n, m, a[N], f[N], dp[N], par[N];
string used[N];
vector<pair<int, int>> vec;
void work(int p){
memset(dp, 0, sizeof dp);
dp[vec.size()] = 1;
vector<int> si;
for (int i = vec.size() - 1; i >= 0; i --){
if (vec[i].second == 1){
if (si.empty()) dp[i] = 0;
else{
int last = si.back();
if (dp[last + 1] and ((vec[last].first - p) <= vec[i].first)){
dp[i] = 1;
par[i] = last + 1;
used[i] = "L";
continue;
}
if (si.size() > 1){
int last2 = si[si.size() - 2];
bool good = ((vec[last2].first - p) <= vec[i].first);
if (si.size() > 2 and vec[si[si.size() - 3]].first <= vec[last].first + p){
if (good and dp[si[si.size() - 3]]){
dp[i] = 1;
par[i] = si[si.size() - 3];
used[i] = "RL";
}
}
else{
int nxt = upper_bound(vec.begin(), vec.end(), (pair<int, int>) {vec[last].first + p, 2}) - vec.begin();
if (good and dp[nxt]){
dp[i] = 1;
par[i] = nxt;
used[i] = "RL";
}
}
}
}
}
else{
if (si.size() and vec[si.back()].first <= vec[i].first + p){
if (dp[si.back()]){
dp[i] = 1;
par[i] = si.back();
used[i] = "R";
}
}
else{
int nxt = upper_bound(vec.begin(), vec.end(), (pair<int, int>) {vec[i].first + p, 2}) - vec.begin();
if (dp[nxt]){
dp[i] = 1;
par[i] = nxt;
used[i] = "R";
}
}
si.push_back(i);
}
}
}
int main(){
cin >> n >> m;
for (int i = 0; i < n; i ++){
cin >> a[i];
vec.push_back({a[i], 0});
}
for (int i = 0; i < m; i ++){
cin >> f[i];
vec.push_back({f[i], 1});
}
sort(vec.begin(), vec.end());
if (n == 1){
int mn = f[0];
int mx = f[m - 1];
if (mn < a[0] and a[0] < mx)
cout << -1 << endl;
else{
if (mx <= a[0]){
if (a[0] == mn)
cout << 1 << endl;
cout << a[0] - mn << endl;
cout << "L" << endl;
}
else{
if (a[0] == mx)
cout << 1 << endl;
cout << mx - a[0] << endl;
cout << "R" << endl;
}
}
return 0;
}
int l = -1;
int r = 1e9;
for (int i = 0; i < 10; i ++){
work(i);
if (dp[0]){
l = i - 1;
r = i;
break;
}
}
while (r - l > 1){
int p = (l + r) / 2;
work(p);
if (dp[0]) r = p;
else l = p;
}
work(r);
cout << r << endl;
int cur = 0;
while (cur < vec.size()){
cout << used[cur];
cur = par[cur];
}
cout << endl;
}
