//~~~~~~~~~~~~~MJ®™~~~~~~~~~~~~~
#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#define rep1(n) for(ll i=0; i<(ll)(n); ++i)
#define rep2(i,n) for(ll i=0; i<(ll)(n); ++i)
#define rep3(i,a,b) for(ll i=(ll)(a); i<(ll)(b); ++i)
#define rep4(i,a,b,c) for(ll i=(ll)(a); i<(ll)(b); i+=(c))
#define cut4(a,b,c,d,e,...) e
#define rep(...) cut4(__VA_ARGS__,rep4,rep3,rep2,rep1)(__VA_ARGS__)
#define per1(n) for(ll i=((ll)n)-1; i>=0; --i)
#define per2(i,n) for(ll i=((ll)n)-1; i>=0; --i)
#define per3(i,a,b) for(ll i=((ll)a)-1; i>=(ll)(b); --i)
#define per4(i,a,b,c) for(ll i=((ll)a)-1; i>=(ll)(b); i-=(c))
#define per(...) cut4(__VA_ARGS__,per4,per3,per2,per1)(__VA_ARGS__)
#define ll long long
#define ln cout<<endl
#define int long long
#define Code ios_base::sync_with_stdio(0);
#define by cin.tie(NULL);
#define Hayan cout.tie(NULL);
#define append push_back
#define all(x) (x).begin(),(x).end()
#define allr(x) (x).rbegin(),(x).rend()
#define vi vector<int>
#define ret(x) {cout<<x;return;}
#define ui map<int,int>
#define pi pair<int,int>
#define ff first
#define ss second
using namespace std;
template <typename T> using v = vector<T>;
const int INF = 1e18, MOD = 1e9+7, N = 2e5+7;
int a[N];
int b[N];
int n, k, e, m, ans = 0;
string s;
bool approved(int k)
{
s.assign(n,'-');
int j=0;
for (int i=0;i<n;i++)
{
while (j<m and (s[i]=='L') and a[i]-k <= b[j] and b[j] <= a[i])
{
j++;
}
while (j<m and (s[i]=='R') and a[i] <= b[j] and b[j] <= a[i] + k)
{
j++;
}
if (s[i]=='-')
{
if (j<m and a[i]-k <= b[j] and b[j] < a[i] )
{
s[i]='L';
j++;
}
else s[i]='R';
}
while (j<m and (s[i]=='L') and a[i]-k <= b[j] and b[j] <= a[i])
{
j++;
}
while (j<m and (s[i]=='R') and a[i] <= b[j] and b[j] <= a[i] + k)
{
j++;
}
}
// cout <<j<<" "<<s<<endl;
return j==m;
}
void solve()
{
cin >> n >> m;
rep(n)
{
cin >> a[i];
}
rep(m)
{
cin>>b[i];
}
int l=-1,r=1e18;
while (r-l>1)
{
int mid=(r+l)/2;
if (approved(mid))
{
r=mid;
}
else l=mid;
}
if (approved(r))
{
cout <<r<<'\n'<<s<<endl;
}
else ret(-1)
// cout << approved(7);
// cout << a.size();
// for (auto i: a){cout << i << " ";}
}
signed main(){
Code by Hayan
int ans=1;
//cout<<setprecision(1000);
// cin>>ans;
rep(ans){
// cout << "Case #" << i+1 << ": ";
solve();ln;}}
