【CodeForces 699A】Launch of Collider

#include <cstdio>
#include <algorithm>
using namespace std;
int n,x,r=-1,ans=-1;
char a[200005];
int main(){
    scanf("%d%s",&n,a);
    for(int i=0;i<n;i++){
        scanf("%d",&x);
        if(a[i]=='R')
            r=x;
        else if(r>-1)
            ans=(ans==-1)?(x-r)/2:min(ans,(x-r)/2);
    }
    printf("%d",ans);
}