#include <bits/stdc++.h>
using namespace std ;
#define is ==
#define isnt !=
#define wnsl '\n'
#define ll long long
const ll sec = 4557430888798830399 ;
#define dbg(...) cerr << "(", dbg_out (#__VA_ARGS__, __VA_ARGS__) ;
template <typename... Args>
void print_args (Args... args) {
((cout << args << " "), ...) ;
cout << wnsl ;
}
void dbg_out () {
cerr << ")" << wnsl ;
}
template <typename Head, typename... Tail>
void dbg_out(const char* names, Head H, Tail... T) {
const char* comma = strchr (names, ',') ;
if (!comma) comma = names + strlen(names) ;
cerr.write (names, comma - names) << " = " << H ;
if constexpr (sizeof...(T) > 0) {
cerr << ", " ;
dbg_out( comma + 1, T...) ;
} else dbg_out () ;
}
void Solve () {
ll n, m ;
cin >> n >> m ;
ll a [n + 1], b [m + 1] ;
for (int i = 1 ; i <= n ; i ++) cin >> a [i] ;
for (int i = 1 ; i <= m ; i ++) cin >> b [i] ;
ll l = 0, r = sec ;
while (l < r) {
ll mid = l + (r - l) / 2 ;
ll p = 1 ;
for (int i = 1 ; i <= n ; i ++) {
if (p <= m and b [p] > a [i] + mid) {
continue ;
}
if (p <= m and b [p] < a [i] - mid) {
continue ;
}
if (p <= m and b [p] < a [i]) {
while (p <= m and b [p] <= a [i]) p ++ ;
} else if (p <= m and b [p] >= a [i]) {
while (p <= m and b [p] - a [i] <= mid) p ++ ;
}
}
if (p > m) r = mid ;
else l = mid + 1 ;
}
if (r is sec) {
cout << -1 << wnsl ;
return ;
} else {
cout << r << wnsl ;
ll p = 1 ;
srand (time (nullptr)) ;
for (int i = 1 ; i <= n ; i ++) {
if (p > m) {
cout << (rand () % 2 is 1 ? 'L' : 'R') ;
continue ;
}
if (b [p] < a [i]) {
cout << 'L' ;
while (p <= m and b [p] <= a [i]) p ++ ;
} else {
cout << 'R' ;
while (p <= m and b [p] - a [i] <= r) p ++ ;
}
}
cout << wnsl ;
}
}
int main () {
ios_base::sync_with_stdio (false) ; cin.tie (nullptr) ; cout.tie (nullptr) ;
Solve () ;
}
