#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int int64_t
int n, m;
vector<int> s, f;
string st;
int so(){
/*if (st!="LLR"){
return 1e18;
}*/
vector<pair<int, int>> je(m, {-1e18, 1e18});
int a=-1e18, in=0;
for (int i=0; i<m; i++){
while (in!=n and s[in]<=f[i]){
if (st[in]=='R'){
a=s[in];
}
in++;
}
je[i].first=a;
//cout<<a<<" "<<in<<"\n";
}
a=1e18;
in=n-1;
for (int i=m-1; i>=0; i--){
while (in!=-1 and s[in]>=f[i]){
if (st[in]=='L'){
a=s[in];
}
in--;
}
je[i].second=a;
}
int ma=-1e18;
for (int i=0; i<m; i++){
int mi=1e18;
if (je[i].first!=-1e18){
mi=min(mi, f[i]-je[i].first);
}
if (je[i].second!=1e18){
mi=min(mi, je[i].second-f[i]);
}
ma=max(ma, mi);
}
/*for (auto u: je){
cout<<"---------------> "<<u.first<<" "<<u.second<<"\n";
}
cout<<st<<" "<<ma<<"\n";*/
return ma;
}
pair<int, string> e(int i){
if (i==n){
return {so(), st};
}
pair<int, string> a={1e18, ""};
st.push_back('L');
a=min(a, e(i+1));
st[st.size()-1]='R';
a=min(a, e(i+1));
st.pop_back();
return a;
}
signed main(){
cin.tie(0); ios_base::sync_with_stdio(NULL);
cin>>n>>m;
s.resize(n);
f.resize(m);
for (int i=0; i<n; i++){
cin>>s[i];
}
for (int i=0; i<m; i++){
cin>>f[i];
}
pair<int, string> a=e(0);
if (a.first==1e18){
cout<<-1<<"\n";
return 0;
}
cout<<a.first<<"\n"<<a.second<<"\n";
}
