#include <stdio.h>

long long min(long long a, long long b){
    return a < b ? a : b;
}

int main(void){
    int n;
    int flag = 0;
    long long second = 100000000;
    char symbol[200010] = {'\0'};
    long long position[20010] = {-1};
    scanf("%d", &n);
    scanf(" %s", symbol);
    for(int i = 0; i < n; i++)
        scanf(" %lld", &position[i]);
    for(int i = 0; i < n - 1; i++){
        if(symbol[i] == 'R' && symbol[i + 1] == 'L'){
            flag = 1;
            second = min(second, (position[i + 1] - position[i]) / 2);
        }
    }
    if(flag)
        printf("%lld\n", second);
    else
        printf("-1\n");
    return 0;
}