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#include <vector>
#include <iostream>
#include <algorithm>
#include <cmath>

using namespace std;

typedef long long ll;

int main() {
  std::ios::sync_with_stdio(false);

  int n, m;
  cin >> n;
  vector<ll> cash(n);

  for (int i = 0; i < n; ++i)
    cin >> cash[i];

  cin >> m;
  string s;
  cin >> s;

  vector<ll> next(m, -1);
  vector<ll> balance(m);
  vector<ll> minNegative(m);
  int cycleLen = 0;
  for (int i = 0; i < m; ++i) {
    if (next[i] == -1) {
      ll localCycleLen = 0;
      ll localBalance = 0;
      ll localMinNegative = 0;
      int pos = i;
      
      do {
        localBalance += (s[pos] == 'W' ? 1 : -1); 
        next[pos] = (pos+n)%m;
        pos = (pos+n)%m;
        localCycleLen++;
        localMinNegative = min(localMinNegative, localBalance);
      } while (next[pos] == -1);

      int tmp = i;
      for (int j = 0; j < localCycleLen; ++j) {
        balance[tmp] = localBalance;
        tmp = (tmp+n)%m;
      }

      minNegative[i] = localMinNegative;
      cycleLen = localCycleLen;
    }

    if (false)
    {  // this makes algorithm O(m^2) it needs improvement
      ll localBalance = 0;
      ll localMin = 0;
      ll pos = i;
      for (int i = 0; i < cycleLen; ++i) {
        localBalance += (s[pos] == 'W' ? 1 : -1);
        pos = (pos+n)%m;
        localMin = min(localMin, localBalance);
      }
      minNegative[i] = localMin;
    }
  }

  /*
  for (auto e : next)
    cout << e << " ";
  cout << endl;

  for (auto e : balance)
    cout << e << " ";
  cout << endl;

  for (auto e : minNegative)
    cout << e << " ";
  cout << endl;
*/
  
  ll minFullCycles = 2e6;
  bool forever = true;
  for (int i = 0; i < n; ++i) {
    if (balance[i%m] < 0 || cash[i] <= minNegative[i%m]) {
      forever = false;
      break;
    }
  }
  if (forever) {
    cout << -1 << endl;
    return 0;
  }

  ll result = 0;
  ll nIdx = 0;
  ll mIdx = 0;
  while (true) {
    result++;
    cash[nIdx] += s[mIdx] == 'W' ? 1 : -1;
    if (cash[nIdx] == 0) break;
    nIdx = (nIdx+1)%n;
    mIdx = (mIdx+1)%m;
  }


  cout << result << endl;
}