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#include <bits/stdc++.h>

using namespace std;

typedef long long LL;

template<typename TH>
void debug_vars(const char* data, TH head){
    cerr << data << "=" << head << "\n";
}

template<typename TH, typename... TA>
void debug_vars(const char* data, TH head, TA... tail){
    while(*data != ',') cerr << *data++;
    cerr << "=" << head << ",";
    debug_vars(data+1, tail...);
}

#ifdef LOCAL
#define debug(...) debug_vars(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (__VA_ARGS__)
#endif

/////////////////////////////////////////////////////////

const int MaxN = 1000005,
          MaxM = 1000005;

const int NoValue = -2,
          Infinity = -1;

LL money[MaxN];
char process[MaxM];
bool visited[MaxM];
LL result[MaxN];
int N, M;

void input(){
    scanf("%d", &N);
    for(int i = 0; i < N; i++){
        scanf("%lld", &money[i]);
    }
    scanf("%d%s", &M, process);
    fill(result, result+N, NoValue);
}


template<typename T>
class cyclic_vector : public vector<T> {
  public:
    using vector<T>::vector;

    inline LL get_id(LL pos) const {
        LL S = (LL)vector<T>::size();
        assert(S > 0);
        return (pos%S+S)%S;
    }

    const T& operator[](LL pos) const { return vector<T>::operator[](get_id(pos)); }
    T& operator[](LL pos) { return vector<T>::operator[](get_id(pos)); }
};



void process_cycle(const vector<int>& cycle){
    int S = (int)cycle.size();
    debug(S);
    string descr(S*2, 0);
    for(int i = 0; i < S; i++){
        descr[i] = descr[i+S] = process[cycle[i]];
    }

    cyclic_vector<vector<int>> levels(2*S+1);
    cyclic_vector<int> positions(2*S+1, 0);
    int pref = 0, lowestPref = 0;
    levels[0].push_back(0);
    for(int i = 0; i < 2*S; i++){
        pref += (descr[i]=='W' ? 1 : -1);
        lowestPref = min(lowestPref, pref);
        levels[pref].push_back(i+1);
    }

    int cycleDiff = pref/2;
    pref = 0;

    // dla kazdej pozycji w cyklu
    for(int i = 0; i < S; i++){
        // bierzemy wszystkich gostkow, ktorzy zaczna z tego miejsca
        for(int guy = cycle[i]; guy < N; guy += M){
            LL cash = money[guy];
            debug(i, guy, cash, pref, lowestPref, cycleDiff);
            if(cycleDiff >= 0){
                if(cash - (pref-lowestPref) >= 1){
                    // ten koles nie zbankrutuje
                    result[guy] = Infinity;
                } else {
                    // znajdujemy pierwszy moment, w ktorym zejdzie do 0
                    LL numPlays = levels[pref-cash][positions[pref-cash]] - i;
                    debug(numPlays);
                    result[guy] = (numPlays-1)*N + guy + 1;
                    debug(result[guy]);
                }
            } else {
                // kiedys na pewno zbankrutuje!
                // na pewno zagra caly cykl pare razy
                LL numPlays = 0;
                LL numCycles = (cash - (pref-lowestPref) - cycleDiff - 1) / abs(cycleDiff);
                if(numCycles < 0) numCycles = 0;
                numPlays += numCycles * (LL)cycle.size();
                LL nowCash = cash + numCycles*cycleDiff;
                debug(numCycles, nowCash, pref-nowCash);

                numPlays += levels[pref-nowCash][positions[pref-nowCash]] - i;
                debug(numPlays);
                result[guy] = (numPlays-1)*N + guy + 1;
            }
        }

        // uaktualniamy dane w 'levels', 'positions' i 'lowestPref'
        positions[pref]++;
        while(positions[lowestPref] == (int)levels[lowestPref].size()) lowestPref++;

        pref += (descr[i] == 'W' ? 1 : -1);
    }
}


void process_cycles(){
    for(int start = 0; start < M; start++){
        if(visited[start]) continue;
        vector<int> cycle;

        int pos = start;
        do {
            cycle.push_back(pos);
            pos = (pos+N)%M;
            visited[pos] = true;
        } while(pos != start);
        process_cycle(cycle);
    }
}

int main(){
    input();
    process_cycles();
    assert(count(result, result+N, NoValue) == 0);

    if(count(result, result+N, Infinity) == N){
        printf("-1\n");
    } else {
        LL res = numeric_limits<LL>::max();
        for(int i = 0; i < N; i++){
            if(result[i] != Infinity) res = min(res, result[i]);
        }
        printf("%lld\n", res);
    }
}