#include<bits/stdc++.h>
#define debug(x) cerr << #x << " " << x << "\n"
#define debugs(x) cerr << #x << " " << x << " "
#pragma GCC optimize("Ofast")
#define int long long
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int range_rng(int l, int r)
{
return uniform_int_distribution<int>(l,r)(rng);
}
int s[100005];
bool done[100005];
int f[100005];
int furthest[100005];
int group[100005];
int groupend[100005];
int groupsz[100005];
vector<int> ls,rs;
string bigmeeks;
int n,m;
bool is_between(int l, int r)
{
int re,pas;
re=0;
pas=(1<<16);
while (pas)
{
if (re+pas<=n && f[re+pas]<l)
re+=pas;
pas=pas/2;
}
re++;
if (re<=n && l<=f[re] && f[re]<=r)
return 1;
else
return 0;
}
bool ok(int k)
{
int i,r,pas,bound,last,j,furthest1,l;
bool oke;
for (i=1; i<=m; i++)
{
r=0;
pas=(1<<16);
while(pas)
{
if (r+pas<=n && s[r+pas]<f[i])
r+=pas;
pas=pas/2;
}
r++;
if (r<=n)
{
bound=groupend[r];
r=0;
pas=(1<<16);
while(pas)
{
if (r+pas<=bound && s[r+pas]<=f[i]+k)
r+=pas;
pas=pas/2;
}
furthest[i]=r;
}
else
{
furthest[i]=n+1;
}
}
string config;
config="$";
for (i=1; i<=n; i++)
config+='R';
for (i=1; i<=m; i++)
done[i]=0;
j=1;
last=0;
for (i=1;i<=m;i++)
{
if (!done[i])
{
furthest1=furthest[i];
if (furthest1==n+1)
continue;
if (groupsz[group[furthest1]]==1)
{
for (l=last+1;l<=furthest1;l++)
config[l]='L';
while (j<=m && f[j]<=s[furthest1])
{
done[j]=1;
j++;
}
last=furthest1;
}
else if (groupsz[group[furthest1]]==2)
{
for (l=last+1;l<=furthest1-1;l++)
config[l]='R';
config[furthest1]='L';
while (j<=m && f[j]<=s[furthest1])
{
done[j]=1;
j++;
}
while (j<=m && f[j]<=s[furthest1-1]+k)
{
done[j]=1;
j++;
}
last=furthest1;
}
else if (groupsz[group[furthest1]]>2)
{
for (l=last+1;l<=furthest1-2;l++)
config[l]='R';
config[furthest1-1]='L';
config[furthest1]='R';
while (j<=m && f[j]<=s[furthest1])
{
done[j]=1;
j++;
}
while (j<=m && f[j]<=s[furthest1]+k)
{
done[j]=1;
j++;
}
last=furthest1;
}
}
}
ls.clear();
rs.clear();
for (i=1;i<=n;i++)
{
if (config[i]=='L')
ls.push_back(s[i]);
else
rs.push_back(s[i]);
}
oke=true;
for (i=1;i<=m;i++)
{
r=-1;
pas=(1<<16);
while (pas)
{
if (r+pas<rs.size() && rs[r+pas]<=f[i])
r+=pas;
pas=pas/2;
}
if (r==-1 || rs[r]+k<f[i])
{
r=-1;
pas=(1<<16);
while (pas)
{
if (r+pas<ls.size() && ls[r+pas]<=f[i])
r+=pas;
pas=pas/2;
}
r++;
if (ls[r]>f[i] && ls[r]-k>f[i] || ls[r]<f[i])
oke=false;
}
}
if (oke)
bigmeeks=config;
return oke;
}
signed main()
{
/*
ifstream fin("arbore.in");
ofstream fout("arbore.out");
*/
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int i,j,cnt,r,pas;
cin >> n >> m;
for (i=1; i<=n; i++)
cin >> s[i];
for (i=1; i<=m; i++)
cin >> f[i];
cnt=1;
group[1]=cnt;
groupend[cnt]=1;
groupsz[cnt]++;
for (i=2; i<=n; i++)
{
if (!is_between(s[i],s[i-1]))
{
cnt++;
}
group[i]=cnt;
groupend[i]=i;
groupsz[cnt]++;
}
if (!ok(1e9))
{
cout << "-1";
}
else
{
r=0;
pas=(1<<30);
while(pas)
{
if (!ok(r+pas))
r+=pas;
pas=pas/2;
}
r++;
ok(r);///stiu ca e cringe da na
cout << r << "\n";
for (i=1;i<=n;i++)
cout << bigmeeks[i];
}
return 0;
}
