#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll mod = 1e9 + 7;
template <typename A, typename B>
string to_string(pair<A, B> p);
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
string to_string(const string& s) { return '"' + s + '"'; }
string to_string(const char c) { return string(1, c); }
string to_string(const char* s) { return to_string((string)s); }
string to_string(bool b) { return (b ? "true" : "false"); }
string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}
template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (int i = int(N) - 1; i >= 0; --i) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto& x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " +
         to_string(get<2>(p)) + ")";
}
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " +
         to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
void debug_out() { cerr << '\n'; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  ll n;
  cin >> n;
  string s;
  cin >> s;
  vector<ll> A(n);
  for (auto& _a : A) cin >> _a;
  vector<int> left, right;
  for (int i = 0; i < n; ++i) {
    if (s[i] == 'L') {
      left.push_back(A[i]);
    } else {
      right.push_back(A[i]);
    }
  }
  if (0) {
  };
  if (0) {
  };
  sort(left.begin(), left.end());
  sort(right.begin(), right.end());
  int nl = left.size(), nr = right.size();
  ll ans = INT_MAX;
  for (int r = 0; r < nr; ++r) {
    auto it = lower_bound(left.begin(), left.end(), right[r]);
    if (it != left.end()) {
      ans = min(ans, ll(*it - right[r]) / 2);
    }
  }
  if (ans == INT_MAX) ans = -1;
  cout << ans << '\n';
}
