#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
struct pair_hash{
size_t operator()(const pair<int,int>&x)const{
return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32));
}
};
int n, m;
vi a, b;
string ans = "";
bool check(int K){
//b - kwiatki
int wsk1 = 0;
int wsk2 = 0;
int range = -1;
ans = "";
while(true){
while(wsk2 < sz(b) && b[wsk2] <= range){
wsk2++;
}
while(wsk1 < sz(a) && wsk2 < sz(b) && a[wsk1] <= b[wsk2]){
range = max(range, a[wsk1] + K);
ans.pb('R');
wsk1++;
while(wsk2 < sz(b) && b[wsk2] <= range){
wsk2++;
}
}
if(wsk2 == sz(b)){
while(sz(ans) != sz(a)){
ans.pb('L');
}
return true;
}
if(wsk1 == sz(a)){
return range >= b.back();
}
if(a[wsk1] - K > b[wsk2]){
return false;
}
int pocz = wsk1;
while(wsk1 + 1 < sz(a) && a[wsk1 + 1] - K <= b[wsk2]){
wsk1++;
}
if(pocz == wsk1){
ans.pb('L');
range = max(range, a[wsk1]);
wsk1++;
}else if(wsk1 == pocz + 1){
int f = 0;
while(wsk2 < sz(b) && b[wsk2] <= a[pocz]){
wsk2++;
}
if(wsk2 < sz(b) && b[wsk2] < a[wsk1]){
f = 1;
}
if(f){
ans.pb('R');
ans.pb('L');
range = max(range, max(a[wsk1], a[pocz] + K));
}else{
ans.pb('L');
ans.pb('R');
range = max(range, a[wsk1] + K);
}
wsk1++;
}else{
string add = "";
for(int j = pocz; j <= wsk1; j++){
add.pb('R');
}
add[sz(add) - 2] = 'L';
ans += add;
range = max(range, a[wsk1] + K);
wsk1++;
}
}
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
cin >> n >> m;
a.resize(n);
for(int i = 0; i < n; i++){
cin >> a[i];
}
b.resize(m);
for(int i = 0; i < m; i++){
cin >> b[i];
}
int l = 0;
int p = (int)1e9;
int mid;
while(l < p){
mid = (l + p) / 2;
if(check(mid)){
p = mid;
}else{
l = mid + 1;
}
}
if(!check(l)){
cout << "-1\n";
return 0;
}
cout << l << '\n';
cout << ans << '\n';
return 0;
}
