#include <iostream>
using namespace std;
int s[100001];
int f[100001],n,m;
pair<int,int> dp[100001][2];
bool vf(int k){
int p1=1,p2=1,p3=1,i;
dp[0][0]=dp[0][1]={1,0};
for(i=1;i<=n;i++){
while(p1<=m && f[p1]<=s[i])
p1++;
while(p2<=m && f[p2]<=s[i-1]+k)
p2++;
while(p3<=m && f[p3]<=s[i]+k)
p3++;
dp[i][0]=dp[i][1]=max(make_pair(dp[i-1][0].first,0),
make_pair(dp[i-1][1].first,1));
if(f[dp[i-1][0].first]>=s[i])
dp[i][1]=max(dp[i][1],{p3,0});
if(f[dp[i-1][1].first]>=s[i])
dp[i][1]=max(dp[i][1],{p3,1});
if(f[dp[i-1][0].first]>=s[i]-k)
dp[i][0]=max(dp[i][0],{p1,0});
if(f[dp[i-1][1].first]>=s[i]-k)
dp[i][0]=max(dp[i][0],{max(p1,p2),1});
}
if(max(dp[n][0].first,dp[n][1].first)>m) return 1;
return 0;
}
int main()
{
int st=0,dr=1e9,rasp=-1,i,mij,aux;
string rasp1;
cin>>n>>m;rasp1.resize(n);
for(i=1;i<=n;i++) cin>>s[i];
for(i=1;i<=m;i++) cin>>f[i];
s[0]=-1e9;f[m+1]=19;
while(st<=dr){
mij=(st+dr)/2;
if(vf(mij)){
rasp=mij;dr=mij-1;
}else st=mij+1;
}
if(rasp!=-1){
vf(rasp);
if(dp[n][1]>dp[n][0]) aux=1;
else aux=0;
for(i=n;i>=1;i--){
if(!aux) rasp1[i-1]='L';
else rasp1[i-1]='R';
aux=dp[i][aux].second;
}
cout<<rasp<<"\n"<<rasp1;
return 0;
}
cout<<"-1";
return 0;
}
