#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int, int>
vector<int> flowers;
vector<int> sprinklers;
int under(vector<int>& v, int x){
int res =0;
for(int step= (1<<20); step>=1; step/=2){
if(res + step < v.size() && v[res+step]<=x){
res+= step;
}
}
return res;
}
int above(vector<int>& v, int x){
int res =v.size()-1;
for(int step= (1<<20); step>=1; step/=2){
if(res - step >=0 && v[res-step]>=x){
res-= step;
}
}
return res;
}
pii get_coverage(pii interval){
return {above(flowers, interval.first), under(flowers, interval.second)};
}
bool is_in(pii inter, int pos){
return (pos>=inter.first && pos<=inter.second);
}
int N, M;
struct DP{
int val= 0;
int anc =0;
string p;
DP(){};
DP(int _val, int _anc, string s){
p = s;
val = _val;
anc= _anc;
}
};
void chmax(DP& a, DP b){
if(b.val>a.val){
a= b;
}
}
vector<DP> solve(int k){
vector<DP> dp(N+1);
for(int cur_sprinkler = 0; cur_sprinkler<N; cur_sprinkler++){
int uncovered_flower = dp[cur_sprinkler].val;
pii before_inter = get_coverage({sprinklers[cur_sprinkler]-k, sprinklers[cur_sprinkler]});
if(is_in(before_inter, uncovered_flower)){
chmax(dp[cur_sprinkler+1], DP(before_inter.second+1, cur_sprinkler, string("L")));
}
before_inter = get_coverage({sprinklers[cur_sprinkler], sprinklers[cur_sprinkler]+k});
if(is_in(before_inter, uncovered_flower)){
chmax(dp[cur_sprinkler+1], DP(before_inter.second+1, cur_sprinkler, string("R")));
}
if(cur_sprinkler<N-1){
if(sprinklers[cur_sprinkler+1]-sprinklers[cur_sprinkler]<k){
pii interval = {sprinklers[cur_sprinkler+1]-k, sprinklers[cur_sprinkler]+k};
if(is_in(get_coverage(interval), uncovered_flower)){
chmax(dp[cur_sprinkler+2], DP(before_inter.second+1, cur_sprinkler, string("LR")));
}
}
}
chmax(dp[cur_sprinkler+1], DP(uncovered_flower, cur_sprinkler, string("R")));
}
return dp;
}
string res;
void backtrack(vector<DP>& dp, int pos){
bool ok = true;
while(ok){
res.append(dp[pos].p.begin(), dp[pos].p.end());
pos= dp[pos].anc;
ok = pos>0;
}
}
signed main(){
cin>>N>>M;
sprinklers.resize(N);
for(int i = 0; i<N; i++){
cin>>sprinklers[i];
}
int k;
flowers.push_back(sprinklers[0]);
for(int i = 0; i<M; i++){
cin>>k;
flowers.push_back(k);
}
flowers.push_back(sprinklers.back());
sort(flowers.begin(), flowers.end());
int K=1e9;
for(int step = (1<<30); step>=1; step/=2){
if(K-step>=0 && solve(K-step).back().val == M+2){
K-=step;
}
}
cout<<K<<endl;
auto res_dp = solve(K);
backtrack(res_dp, N);
reverse(res.begin(), res.end());
cout<<res<<endl;
}
