#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define MOD 1000000007
const int N = 100010;
int s[N], f[N], dp[N][8], n, m;
bool check(int K){
int ind = 0;
for(int i = 3; i < n; i++){
for(int mask = 0; mask < (1 << 3); mask++){
dp[i][mask] = -1;
for (int typ = 0; typ < 2; typ++){
if(dp[i - 1][(mask + (typ == 1) * 8) >> 1] == -1){
continue;
}
bool ch = 1;
for(int tmp = ind; tmp < m and f[tmp] <= s[i-1]; tmp++){
ll flg = 0;
for(int k = i - 3; k <= i; k++){
if(f[tmp] == s[k]){
flg = 1;
break;
}
if((f[tmp] >= s[k]) == (((mask + (typ == 1) * 8) >> (i - k)) & 1) and abs(f[tmp] - s[k]) <= K){
flg = 1;
break ;
}
}
if(flg){
continue;
}
else{
ch = 0;
break ;
}
}
if(!ch){
continue;
}
dp[i][mask] = (mask + (typ == 1) * 8) >> 1;
}
}
while(ind < m and f[ind] <= s[i-1]){
ind++;
}
}
return dp[n - 1][0] != -1;
}
void solve(){
cin >> n >> m;
s[0] = s[1] = s[2] = -2e9;
for(int i = 3 ;i < n + 3; i ++){
cin >> s[i];
}
s[n + 3] = s[n + 4] = s[n + 5] = 2e9;
for(int i = 0 ;i < m; i ++){
cin >> f[i];
}
n += 6;
int l = -1, r = 1e9 + 5;
while(r - l > 1){
int mid = (l + r) / 2;
if(check(mid)){
r = mid;
}
else{
l = mid;
}
}
if(r == 1e9 + 5){
cout << -1 << '\n';
}
else{
check(r);
string ans(n, 'L');
int j = 0;
for(int i = n - 1; i >= 0; i--){
if(j % 2){
ans[i] = 'R';
}
else{
ans[i] = 'L';
}
j = dp[i][j];
}
cout << r << '\n';
for(int i = 3; i < n - 3; i ++){
cout << ans[i];
}
cout << '\n';
}
}
int main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
ll tests = 1;
// cin >> tests;
for(ll i = 1; i <= tests; i++){
solve();
}
}
