#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define replr(i, a, b) for (int i = int(a); i <= int(b); ++i)
#define reprl(i, a, b) for (int i = int(a); i >= int(b); --i)
#define rep(i, n) for (int i = 0; i < int(n); ++i)
#define mkp(a, b) make_pair(a, b)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VPI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<VPI> VVPI;
typedef pair<ll, ll> PLL;
typedef vector<ll> VL;
typedef vector<PLL> VPL;
typedef vector<VL> VVL;
typedef vector<VVL> VVVL;
typedef vector<VPL> VVPL;
template<class T> T setmax(T& a, T b) {if (a < b) return a = b; return a;}
template<class T> T setmin(T& a, T b) {if (a < b) return a; return a = b;}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template<class T>
using indset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef vector<char> VC;
typedef vector<VC> VVC;
typedef vector<bool> VB;
typedef vector<VB> VVB;
bool checkcover(VI& a, VPI& ranges) {
/* khamarem or erkusn el sortavorac en*/
int i = 0;
for (auto[L, R] : ranges) {
if (a[i] < L) return false;
while (i < a.size() && a[i] <= R) i++;
if (i == a.size()) break;
}
return i == a.size();
}
void solve() {
int n, m;
cin >> n >> m;
VI a(n);
/* jur */
VI b(m);
/* caxik */
for (int& x : a) cin >> x;
for (int& x : b) cin >> x;
string ans(n, 'R');
for (int i = 0; i < a.size(); i += 3) ans[i] = 'L';
auto can = [&](ll d) {
VPI ranges;
for (int i = 0; i < a.size(); i += 3) {
ranges.pb({a[i]-d, a[i]+d});
}
return checkcover(b, ranges);
};
/*replr(i, 0, 10) cout << can(i) << endl;*/
ll l = -1, r = 2e9;
while (l + 1 < r) {
ll m = (l + r) / 2;
if (can(m)) r = m;
else l = m;
}
if (r == 2e9) cout << -1 << endl;
else {
can(r);
cout << r << endl;
cout << ans << endl;
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL), cout.tie(NULL);
/*freopen("mincross.in", "r", stdin); */
/*freopen("test.out", "w", stdout); */
int t = 1;
/*cin >> t; */
while (t--) solve();
}
