#include <bits/stdc++.h>
using namespace std;
struct range {
int l, r;
};
const int MAX_N = 1e5;
const int MAX_D = 1e9;
const int MIN_D = 0;
int n, m;
int s[MAX_N + 1], f[MAX_N + 1];
range rightReach[MAX_N + 1], leftReach[MAX_N + 1];
int dp[1001][1001];
char last[1001][1001];
bool solve( int d, bool printSol ) {
int j = 0;
for ( int i = 1; i <= n; i++ ) {
while ( j <= m && f[j] < s[i] - d )
j++;
leftReach[i].l = j;
}
j = 0;
for ( int i = 1; i <= n; i++ ) {
while ( j + 1 <= m && f[j + 1] <= s[i] + d )
j++;
rightReach[i].r = j;
}
j = 0;
for ( int i = 1; i <= n; i++ ) {
while ( j + 1 <= m && f[j + 1] <= s[i] )
j++;
leftReach[i].r = j;
}
j = 0;
for ( int i = 1; i <= n; i++ ) {
while ( j <= m && f[j] < s[i] )
j++;
rightReach[i].l = j;
}
for ( int i = 0; i <= n; i++ ) {
for ( int j = 0; j <= m; j++ )
dp[i][j] = (j == 0), last[i][j] = 'L';
}
for ( int i = 1; i <= n; i++ ) {
// i merge la stanga
for ( int j = 0; j < m; j++ ) {
//eu am acoperit pana la j deci acopar (j+1, leftReach[i].r) si eventual mai mult
if ( !dp[i - 1][j] )
continue;
if ( j + 1 > leftReach[i].r )
continue;
if ( s[i] - f[j + 1] > d )
continue;
int k = leftReach[i].r;
if ( leftReach[i - 1].l <= j + 1 )
k = rightReach[i - 1].r;
dp[i][k] = true;
last[i][k] = 'L';
}
// i merge la dreapta
for ( int j = 0; j < m; j++ ) {
if ( !dp[i - 1][j] )
continue;
int k = j;
if ( rightReach[i].l <= j + 1 )
k = rightReach[i].r;
dp[i][k] = true;
last[i][k] = 'R';
}
for ( int j = m - 1; j >= 0; j-- ) {
dp[i][j] |= dp[i][j + 1];
if ( dp[i][j + 1] )
last[i][j] = last[i][j + 1];
}
}
j = m;
string sol = "";
for ( int i = n; i >= 1; i-- ) {
sol += last[i][j];
if ( last[i][j] == 'R' )
j = rightReach[i].l - 1;
else
j = leftReach[i].l - 1;
}
reverse( sol.begin(), sol.end() );
if ( printSol )
cout << sol << "\n";
#ifdef LOCAL
printf( "---------D %d--------\n", d );
for ( int i = 1; i <= n; i++ ) {
printf( "%d %d %d %d\n", leftReach[i].l, leftReach[i].r, rightReach[i].l, rightReach[i].r );
}
for ( int i = 1; i <= n; i++ ) {
for ( int j = 0; j <= m; j++ )
printf( "%d", dp[i][j] );
printf( "\n" );
}
#endif
return dp[n][m];
}
int main() {
cin.tie( nullptr );
ios_base::sync_with_stdio( false );
cin >> n >> m;
for ( int i = 1; i <= n; i++ )
cin >> s[i];
for ( int i = 1; i <= m; i++ )
cin >> f[i];
int l = MIN_D - 1, r = MAX_D + 1;
while ( r - l > 1 ) {
int mid = (l + r) / 2;
if ( solve( mid, false ) )
r = mid;
else
l = mid;
}
if ( r == MAX_D + 1 )
cout << "-1\n";
else {
cout << r << "\n";
solve( r, true );
}
return 0;
}
