#include <iostream>
#include <vector>
#include <algorithm>
#include <cassert>
using ll = long long;
#define debug(x) #x << " = " << x << '\n'
int main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
#endif
std::ios_base::sync_with_stdio(false);
std::cin.tie(0);
int n, m;
std::cin >> n >> m;
std::vector<int> s(n), f(m);
for (int &x : s) {
std::cin >> x;
}
for (int &x : f) {
std::cin >> x;
}
std::vector<char> type(n);
auto check = [&](int K) {
std::vector<bool> watered(m, false);
for (int i = 0, j = 0; i < n; i++) {
while (j < m && watered[j]) {
j++;
}
if (j == m) {
type[i] = 'L';
continue;
}
if (f[j] < s[i]) {
type[i] = 'L';
// ma pun spre stanga
if (f[j] < s[i] - K) {
return false;
}
while (j < m && f[j] <= s[i]) {
watered[j] = true;
j++;
}
} else {
type[i] = 'R';
// ma pun spre dreapta
while (j < m && f[j] <= s[i] + K) {
watered[j] = true;
j++;
}
}
}
return std::count(watered.begin(), watered.end(), true) == m;
};
if (!check(1e9 + 1)) {
std::cout << -1;
return 0;
}
int l = 0, r = 1e9;
while (l < r) {
int mid = (l + r) / 2;
if (check(mid)) {
r = mid;
} else {
l = mid + 1;
}
}
check(r);
std::cout << r << '\n';
for (char c : type) {
std::cout << c;
}
return 0;
}
