#include <bits/stdc++.h>
using namespace std;
int n,arr[200050],minn=INT_MAX;
string s;
int main(){
cin>>n;
cin>>s;
s='0'+s;
for(int i=1;i<=n;i++){
cin>>arr[i];
}
for(int i=1;i<=n;i++){
if(s[i]=='R' && s[i+1]=='L'){
minn=min((arr[i+1]-arr[i])/2,minn);
}
}
if(minn==INT_MAX){
cout<<-1;
return 0;
}
cout<<minn;
return 0;
}
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