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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class haz {
    BufferedReader rd;
    int[][] st;

    haz() throws IOException {
        rd = new BufferedReader(new InputStreamReader(System.in));
        out(compute());
    }

    private long compute() throws IOException {
        rd.readLine();
        int[] a = intarr();
        int n = a.length;
        rd.readLine();
        char[] s = rd.readLine().toCharArray();
        int m = s.length;

        int g = gcd(n,m);
        int mg = m/g;
        int[] p = new int[mg];
        int c = n % m;
        int pos = 1;
        while(c != 0) {
            p[pos] = c;
            c = (c+n)%m;
            pos++;
        }
        List[] backs = new List[g];
        for(int j=0;j<g;j++) {
            backs[j] = new ArrayList<int[]>(1);
        }
        for(int v=0;v<mg;v++) {
            for(int w=0;w<g;w++) {
                if(p[v] < n) {
                    int st = p[v]+w;
                    while(st < n) {
                        backs[w].add(new int[] { st, (v)%mg });
                        st += m;
                    }
                }
            }
        }
        long ln = n;
        long minSteps = Long.MAX_VALUE;
        int[] sc = new int[Integer.highestOneBit(2*mg + 1)<<1];
        Arrays.fill(sc, 2*mg+1, sc.length, 1_000_000_000);
        alloc(sc);
        for(int b=0;b<g;b++) {
            for(int i=0;i<2*mg;i++) {
                sc[i+1] = sc[i] + (s[p[i%mg]+b]=='W'?1:-1);
            }
            init(sc);

            int cycleDiff = sc[mg];
            for(Object vv: backs[b]) {
                int[] v = (int[])vv;
                int i = v[0];
                int start = v[1];
                int min = query(sc, start, start + mg) - sc[start];
                if(min < 0) {
                    long tm = i;
                    long cur = a[i];
                    boolean endless = false;
                    if(cur + min > 0) {
                        if(cycleDiff < 0) {
                            long cycles = (cur + min) / -cycleDiff + 1;
                            if(((cur+min) % -cycleDiff) == 0) {
                                cycles--;
                            }
                            tm += cycles * mg * ln;
                            cur += cycleDiff * cycles;
                        } else {
                            endless = true;
                        }
                    }
                    if(!endless) {
                        int ev = (int)-cur;
                        int from = start;
                        int to = start + mg;
                        while(to - from > 1) {
                            int mid = (from + to) / 2;
                            if(query(sc, from, mid) - sc[start] > ev) {
                                from = mid+1;
                            } else {
                                to = mid;
                            }
                        }
                        for(int k=from;k<=Math.max(from,to);k++) {
                            if(sc[k] - sc[start] <= ev) {
                                tm += (k - start - 1) * ln + 1;
                                break;
                            }
                        }
                        minSteps = Math.min(minSteps, tm);
                    }
                }
            }
        }
        return minSteps==Long.MAX_VALUE?-1:minSteps;
    }

    private void alloc(int[] a) {
        int n = a.length;
        int ml = Integer.numberOfTrailingZeros(Integer.highestOneBit(n))+1;
        st = new int[n][ml];
    }

    private void init(int[] a) {
        int n = a.length;
        int ml = Integer.numberOfTrailingZeros(Integer.highestOneBit(n))+1;
        for(int i=0;i<n;i++) {
            st[i][0] = i;
        }
        for(int j = 1;j < ml;j++) {
            for(int i = 0; i + (1 << j) - 1 < n;i++) {
                if(a[st[i][j-1]] < a[st[i + (1 << (j-1))][j-1]]) {
                    st[i][j] = st[i][j-1];
                } else {
                    st[i][j] = st[i + (1 << (j-1))][j-1];
                }
            }
        }
    }

    private int query(int[] a, int left, int right) {
        int c = right - left + 1;
        int d = Integer.numberOfTrailingZeros(Integer.highestOneBit(c));
        return Math.min(a[st[left][d]], a[st[right-(1<<d)+1][d]]);
    }

    private int gcd(int a, int b) {
        while (b > 0) {
            int c = a % b;
            a = b;
            b = c;
        }
        return a;
    }

    private int[] intarr() throws IOException {
        return intarr(rd.readLine());
    }

    private int[] intarr(String s) {
        String[] q = split(s);
        int n = q.length;
        int[] a = new int[n];
        for(int i=0;i<n;i++) {
            a[i] = Integer.parseInt(q[i]);
        }
        return a;
    }

    public String[] split(String s) {
        if(s == null) {
            return new String[0];
        }
        int n = s.length();
        int start = -1;
        int end = 0;
        int sp = 0;
        boolean lastWhitespace = true;
        for(int i=0;i<n;i++) {
            char c = s.charAt(i);
            if(isWhitespace(c)) {
                lastWhitespace = true;
            } else {
                if(lastWhitespace) {
                    sp++;
                }
                if(start == -1) {
                    start = i;
                }
                end = i;
                lastWhitespace = false;
            }
        }
        if(start == -1) {
            return new String[0];
        }
        String[] res = new String[sp];
        int last = start;
        int x = 0;
        lastWhitespace = true;
        for(int i=start;i<=end;i++) {
            char c = s.charAt(i);
            boolean w = isWhitespace(c);
            if(w && !lastWhitespace) {
                res[x++] = s.substring(last,i);
            } else if(!w && lastWhitespace) {
                last = i;
            }
            lastWhitespace = w;
        }
        res[x] = s.substring(last,end+1);
        return res;
    }

    private boolean isWhitespace(char c) {
        return c==' ' || c=='\t';
    }

    private static void out(Object x) {
        System.out.println(x);
    }

    public static void main(String[] args) throws IOException {
        new haz();
    }
}