#include <bits/stdc++.h>
#define int long long
using namespace std;
int n, m;
string ans;
vector<int> s, f;
bool check(int x) {
for (int mask = 0; mask < (1 << n); mask++) {
for (int i = 0; i < n; i++) {
ans[i] = ((mask & (1 << i)) ? 'R' : 'L');
}
vector<bool> ok(m);
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (ans[i] == 'L') {
ok[j] = ok[j] || (s[i] - x <= f[j] && f[j] <= s[i]);
} else {
ok[j] = ok[j] || (s[i] <= f[j] && f[j] <= s[i] + x);
}
}
}
bool aok = 1;
for (int i = 0; i < m; i++) aok = aok && ok[i];
if (aok) return 1;
}
return 0;
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
s.resize(n);
f.resize(m);
for (int i = 0; i < n; i++) cin >> s[i];
for (int i = 0; i < m; i++) cin >> f[i];
for (int i = 0; i < n; i++) ans += '_';
int l = -1, r = 1e10;
while (r - l > 1) {
int md = (r + l) / 2;
if (check(md)) {
r = md;
} else {
l = md;
}
}
if (r == 1e10) {
cout << "-1\n";
} else {
check(r);
cout << r << "\n" << ans << "\n";
}
}
