#include <bits/stdc++.h>
using namespace std;
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int n,m;
cin >> n >> m;
long long arr[n],brr[m];
for(int i=0; i<n; i++) cin >> arr[i];
for(int i=0; i<m; i++) cin >> brr[i];
long long lo=0,hi=1e9+5,mid;
while(lo<hi){
mid=(lo+hi)/2;
pair<int,int> l[n+1],r[n+1];
int c1=0,c2=-1,c3=0,c4=-1;
for(int i=0; i<n; i++){
while(c1<m&&brr[c1]<arr[i]-mid) c1++;
while(c2+1<m&&brr[c2+1]<=arr[i]) c2++;
while(c3<m&&brr[c3]<arr[i]) c3++;
while(c4+1<m&&brr[c4+1]<=arr[i]+mid) c4++;
l[i+1]={c1,c2}; r[i+1]={c3,c4};
}
int dp[n+1];
memset(dp,-1,sizeof(dp));
for(int i=1; i<=n; i++){
//R
if(dp[i-1]+1>=r[i].first) dp[i]=max(dp[i],r[i].second);
//L in general
if(dp[i-1]+1>=l[i].first) dp[i]=max(dp[i],l[i].second);
//RL
if(i>1&&dp[i-2]+1>=l[i].first) dp[i]=max(dp[i],r[i-1].second);
}
if(dp[n]>=m-1) hi=mid;
else lo=mid+1;
}
if(lo>1e9){
cout << -1;
return 0;
}
cout << lo << '\n';
mid=lo;
pair<int,int> l[n+1],r[n+1];
int c1=0,c2=-1,c3=0,c4=-1;
for(int i=0; i<n; i++){
while(c1<m&&brr[c1]<arr[i]-mid) c1++;
while(c2+1<m&&brr[c2+1]<=arr[i]) c2++;
while(c3<m&&brr[c3]<arr[i]) c3++;
while(c4+1<m&&brr[c4+1]<=arr[i]+mid) c4++;
l[i+1]={c1,c2}; r[i+1]={c3,c4};
}
int dp[n+1],st[n+1];
memset(dp,-1,sizeof(dp));
for(int i=1; i<=n; i++){
//R
if(dp[i-1]+1>=r[i].first&&dp[i]<r[i].second){
dp[i]=r[i].second;
st[i]=1;
}
//L in general
if(dp[i-1]+1>=l[i].first&&dp[i]<l[i].second){
dp[i]=l[i].second;
st[i]=2;
}
//RL
if(i>1&&dp[i-2]+1>=l[i].first&&dp[i]<r[i-1].second){
dp[i]=r[i-1].second;
st[i]=3;
}
}
char ans[n+1];
int cur=n;
while(cur>=1){
if(st[cur]==1){
ans[cur]='R';
cur--;
}
else if(st[cur]==2){
ans[cur]='L';
cur--;
}
else{
ans[cur]='L';
ans[cur-1]='R';
cur-=2;
}
}
for(int i=1; i<=n; i++) cout << ans[i];
}
