#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[MAX_N + 1];
char last[MAX_N + 1];
bool solve( int d, bool printSol ) {
int j = 1;
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 = 1;
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++ ) {
dp[i] = 0;
last[i] = 'L';
}
for ( int i = 1; i <= n; i++ ) {
// am acoperit pana la dp[i - 1]
//incerc stanga
if ( leftReach[i].l <= dp[i - 1] + 1 ) {
int k = leftReach[i].r;
if ( rightReach[i - 1].l > dp[i - 1] + 1 )
k = max( k, rightReach[i - 1].r );
if ( k > dp[i] ) {
dp[i] = k;
last[i] = 'L';
}
}
//incerc dreapta
if ( rightReach[i].l <= dp[i - 1] + 1 ) {
int k = rightReach[i].r;
if ( k > dp[i] ) {
dp[i] = k;
last[i] = 'R';
}
}
}
int k = m;
string sol = "";
for ( int i = 1; i <= n; i++ )
sol += last[i];
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 = 0; i <= n; i++ )
printf( "%d %c\n", dp[i], last[i] );
#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;
}
