#include<bits/stdc++.h>
using namespace std;
#define MAXN 100'007
int n,m;
int s[MAXN];
int f[MAXN];
string otg="";
bool check(int k, bool otp)
{
int len=1<<n;
for (int msk=0;msk<len;msk++)
{
bool dl=true;
for (int q=1;q<=m;q++)
{
bool mg=false;
for (int w=1;w<=n;w++)
{
if ((msk>>(w-1))%2==0 && f[q]<=s[w])
{
if ((s[w]-f[q])<=k) {mg=true;break;}
}
if ((msk>>(w-1))%2==1 && f[q]>=s[w])
{
if ((f[q]-s[w])<=k) {mg=true;break;}
}
}
if (!mg)
{
dl=false;
break;
}
}
if (dl)
{
if (otp)
{
for (int w=0;w<n;w++)
{
if ((msk>>w)%2==0) otg[w]='L';
else otg[w]='R';
}
cout<<otg<<"\n";
}
return true;
}
}
return false;
}
bool check2(int k, bool otp)
{
int lstS=n,lstF=m;
while (true)
{
if (lstF<=0) break;
if (lstS<=0) return false;
//cout<<lstS<<" "<<lstF<<"\n";
if (f[lstF]>s[lstS])
{
///nqkoi trqbva da prysne lstF
int l=0,r=lstS+1;
while (l<r-1)
{
int mid=(l+r)/2;
if (s[mid]<(f[lstF]-k)) l=mid;
else r=mid;
}
if (r==(lstS+1)) return false;
///r e posledniq koito ima umeniqta mi
///sega tyrsim pyrvoto cvete, koeto e po-golqmo ili ravno na r
int ll=0,rr=lstF;
while (ll<rr-1)
{
int mid=(ll+rr)/2;
if (f[mid]>=s[r]) rr=mid;
else ll=mid;
}
///rr e pyrvoto cvete, koeto shte byde hvanato v struqta
///sega tyrsim pyrviq, koito e po-malko ili ravno na rr
int lll=r,rrr=lstS+1;
while (lll<rrr-1)
{
int mid=(lll+rrr)/2;
if (s[mid]<=f[rr]) lll=mid;
else rrr=mid;
}
///lll e tozi koito trqbva da ocveti lstF
otg[lll-1]='R';
int mnn=s[lll];
if (lll!=lstS)
{
for (int q=lll+1;q<=lstS;q++)
{
mnn=min(mnn,s[q]-k);
otg[q-1]='L';
}
}
lstS=lll-1;
while (lstF>=1 && f[lstF]>=mnn) lstF--;
}
else
{
///lstS pryska nalqvo
otg[lstS-1]='L';
while (lstF>=1 && (s[lstS]-f[lstF])<=k) lstF--;
lstS--;
}
}
if (otp)
{
for (int q=0;q<lstS;q++) otg[q]='L';
cout<<otg<<"\n";
}
return true;
}
int main()
{
otg="";
cin>>n>>m;
for (int q=0;q<n;q++) otg+='.';
for (int q=1;q<=n;q++) cin>>s[q];
for (int q=1;q<=m;q++) cin>>f[q];
int l=-1,r=1e9+1;
while (l<r-1)
{
int mid=(l+r)/2;
//cout<<mid<<"\n";
bool ch=check2(mid,0);
if (ch) r=mid;
else l=mid;
}
if (r==(1e9+1)) cout<<"-1\n";
else
{
cout<<r<<"\n";
check2(r,1);
}
}
/*
3 4
10 18 20
10 11 14 24
*/
