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//Pawel Kura
#include <cstdio>
#include <vector>
#include <algorithm>
//#define int long long
using namespace std;
typedef long long LL;


struct sciezka {
    vector<int> a;
    vector<vector<int>> kto;
};
int n;

const int MAXN = 1000000;

int  m;
char s[MAXN + 10];
int h[MAXN + 10];
vector<sciezka> sciezki; 
int reszta[MAXN];
LL kiedy[MAXN];
int mem[4*MAXN];
void rozwal(const sciezka &sci) {
    const auto &a = sci.a;
    int s = a.size();
    vector<int> sumy;
    int prev = 0;
    for (int i = 0; i < 2 * s - 1; i++) {
        prev += a[i % s];
        sumy.push_back(prev);
    }

    static vector<pair<int,int>> deq(2 * MAXN - 1);
    int p, q;
    p = q = deq.size();

    for (int i = 2 * s - 2; i >= s; i--) {
        while (p < q && deq[p].first >= sumy[i]) p++;
        deq[--p] = {sumy[i], i}; 
        mem[-sumy[i]+2*MAXN] = p;
    }
    for (int i = s - 1; i >= 0; i--) {
        while (p < q && deq[q-1].second >= i + s) q--;
        while (p < q && deq[p].first >= sumy[i]) p++;
        deq[--p] = {sumy[i], i};
        mem[-sumy[i]+2*MAXN] = p;
        int fix = (i == 0 ? 0 : sumy[i-1]);
        int mi = deq[q-1].first - fix;
        int su = sumy[i + s - 1] - fix;
        for (auto k: sci.kto[i]) {
            int v = h[k];
            if (su >= 0) {
                if (v + mi > 0) {
                    kiedy[k] = -1;
                } else {
                    int z = mem[v-fix+2*MAXN];
                    auto pos = deq[z].second - i;
                    kiedy[k] = k + 1 + (LL)pos * n; 
                }
            }
            else 
            {
                int licz = max(0, v + mi);
                int mian = -su;
                int obroty = (licz + mian - 1)/mian;

                LL r = v + (LL)obroty * su;
                int z = mem[r-fix+2*MAXN];
                int pos = deq[z].second - i;
                kiedy[k] = k + 1 + 1LL * (pos + 1LL * obroty * s) * n; 
            }
        }
    }

}


int gcd(int a, int b) {
    if (a == 0) return b;
    return gcd(b%a, a);
}
signed main() {
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
        scanf("%d", &h[i]);
    scanf("%d", &m);
    scanf(" %s", s);

    sciezki.resize(gcd(n, m));

    for (int i = 0; i < sciezki.size(); i++) {
        int k = i;
        int z = 0;
        sciezki[i].a.resize(m / sciezki.size());
        do {
            sciezki[i].a[z] = s[k] == 'W' ? 1 : -1;
            reszta[k] = z++;
            k = (k + n) % m;
        } while (k != i);
        sciezki[i].kto.resize(sciezki[i].a.size());
    }

    for (int i = 0; i < n; i++) {
        sciezki[i % sciezki.size()].kto[reszta[i%m]].push_back(i);
    }
    
    for (int i = 0; i < sciezki.size(); i++) {
        rozwal(sciezki[i]);
    }

    LL res = -1;
    for (int i = 0; i < n; i++) {
        if (kiedy[i] != -1 && (kiedy[i] < res || res == -1)) res = kiedy[i];
    }

    printf("%lld\n", res);
    return 0;
}