#include <bits/stdc++.h> using namespace std; using ll = long long; using ld = long double; #define fi first #define se second #define vi vector<int> #define vll vector<long long> #define pii pair<int, int> #define pll pair<long long, long long> #define pb push_back #define mp make_pair #define eb emplace_back #define all(x) (x).begin(), (x).end() #define sz(x) (int)(x).size() mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count()); mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count()); inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);} inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);} #ifdef DEBUG auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";} auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";} #define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X) #else #define debug(...){} #endif struct custom_hash { static uint64_t splitmix64(uint64_t x) { x += 0x9e3779b97f4a7c15; x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9; x = (x ^ (x >> 27)) * 0x94d049bb133111eb; return x ^ (x >> 31); } size_t operator()(uint64_t x) const { static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count(); return splitmix64(x + FIXED_RANDOM); } }; struct pair_hash{ size_t operator()(const pair<int,int>&x)const{ return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32)); } }; const int MAXN = 1e5 + 7; int n, m; vll a; set<pll> b; vll B; string ans = ""; pll dp[MAXN][(1 << 3)]; ll pre[MAXN][(1 << 3)]; int INITIALN; bool inside(int x, int msk, int K, int ind){ for(int j = ind; j <= ind + 2; j++){ if((1 << (2 - (j - ind))) & msk){ if(B[x] >= a[j] && B[x] <= a[j] + K){ return true; } }else{ if(B[x] <= a[j] && B[x] >= a[j] - K){ return true; } } } return false; } bool check(ll K){ for(int i = 0; i < n; i++){ for(int msk = 0; msk < (1 << 3); msk++){ dp[i][msk] = mp(-1LL, -1LL); } } //b - kwiatki for(int msk = 0; msk < (1 << 3); msk++){ int wsk = 0; while(wsk < sz(B) && inside(wsk, msk, K, 0)){ wsk++; } dp[2][msk] = mp(-1LL, -1LL); for(int j = 0; j < 3; j++){ if((1 << j) & msk){ dp[2][msk].se = max(dp[2][msk].se, a[2 - j] + K); }else{ dp[2][msk].se = max(dp[2][msk].se, a[2 - j]); } } dp[2][msk].fi = wsk; } for(int i = 3; i < n; i++){ for(int msk = 0; msk < (1 << 3); msk++){ dp[i][msk] = mp(-1LL, -1LL); pre[i][msk] = -1; pll p[2] = {mp(-1LL, -1LL), mp(-1LL, -1LL)}; for(int prevAdd = 0; prevAdd < 2; prevAdd++){ int prevMsk = msk / 2 + (1 << 2) * prevAdd; if(dp[i - 1][prevMsk].fi < sz(B) && (dp[i - 1][prevMsk].fi == -1 || B[dp[i - 1][prevMsk].fi] < a[i] - K)){ continue; }else if(dp[i - 1][prevMsk].fi == sz(B)){ p[prevAdd] = dp[i - 1][prevMsk]; continue; } if(msk & 1){ //i-ty w prawo p[prevAdd].se = max(dp[i - 1][prevMsk].se, a[i] + K); if(dp[i - 1][prevMsk].fi < sz(B) && B[dp[i - 1][prevMsk].fi] >= a[i]){ auto it = b.upper_bound(mp(p[prevAdd].se, 0)); if(it == b.end()){ p[prevAdd].fi = sz(B); }else{ p[prevAdd].fi = (*it).se; } }else{ p[prevAdd].fi = dp[i - 1][prevMsk].fi; } }else{ //i-ty w lewo p[prevAdd].se = max(dp[i - 1][prevMsk].se, a[i]); if(dp[i - 1][prevMsk].fi < sz(B)){ auto it = b.upper_bound(mp(p[prevAdd].se, 0)); if(it == b.end()){ p[prevAdd].fi = sz(B); }else{ p[prevAdd].fi = (*it).se; } }else{ p[prevAdd].fi = dp[i - 1][prevMsk].fi; } } if(i + 1 < n && p[prevAdd].fi != -1 && p[prevAdd].fi < sz(B) && B[p[prevAdd].fi] < a[i + 1] - K){ p[prevAdd].fi = -1; } } if(p[0].fi == -1 && p[1].fi == -1){ dp[i][msk] = p[0]; }else if(p[0].fi == -1){ dp[i][msk] = p[1]; pre[i][msk] = msk / 2 + (1 << 2); }else if(p[1].fi == -1){ dp[i][msk] = p[0]; pre[i][msk] = msk / 2; }else{ if(p[0].fi != p[1].fi){ if(p[0].fi > p[1].fi){ dp[i][msk] = p[0]; pre[i][msk] = msk / 2; }else{ dp[i][msk] = p[1]; pre[i][msk] = msk / 2 + (1 << 2); } }else{ if(p[0].se > p[1].se){ dp[i][msk] = p[0]; pre[i][msk] = msk / 2; }else{ dp[i][msk] = p[1]; pre[i][msk] = msk / 2 + (1 << 2); } } } } } for(int msk = 0; msk < (1 << 3); msk++){ if(dp[n - 1][msk].fi == sz(B)){ ans = ""; int ind = INITIALN - 1; int curr = msk; while(ind > 2){ if(curr & 1){ ans += "R"; }else{ ans += "L"; } curr = pre[ind][curr]; ind--; } while(ind >= 0){ if(curr & 1){ ans += "R"; }else{ ans += "L"; } ind--; curr /= 2; } reverse(all(ans)); return true; } } return false; } int main(){ ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL); cin >> n >> m; INITIALN = n; a.resize(n); for(int i = 0; i < n; i++){ cin >> a[i]; } while(sz(a) < 3){ a.pb((ll)2e9 + 7); n++; } B = {}; for(int i = 0; i < m; i++){ ll x; cin >> x; B.pb(x); b.insert(mp(x, i)); } int l = 0; int p = (int)1e9; int mid; while(l < p){ mid = (l + p) / 2; if(check(mid)){ p = mid; }else{ l = mid + 1; } } if(!check(l)){ cout << "-1\n"; return 0; } cout << l << '\n'; cout << ans << '\n'; return 0; }