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#include <stdio.h>
#define MIN(a,b) ((a) < (b) ? a : b)
#define INF 0x7fffffffffffffffLL
#define LL (long long)
typedef unsigned char byte;
typedef struct SNode SNode;

struct SNode{
    int curr;
    int fleft;
    int fright;
    int begin;
    int end;
    byte sign;
};

int a[1000002];
char str[1000002];

int pos[1000002];
SNode val[1000002];
byte visi[1000002];
long long ans[1000002];
int tree[2400002],N;

void setVal(int n, int m);
void setInterval(int begin, int end);
void solve(int n, int m);
long long getAns(int x, int a, int n, int m);


int main(void)
{
    int n, m, i;
    scanf("%d",&n);
    for(i = 0; i < n; i++){
        scanf("%d",&a[i]);
    }
    scanf("%d %s",&m,str);

    setVal(n,m);
    solve(n,m);

    return 0;
}

void setInterval(int begin, int end)
{
    int lprev = MIN(val[begin].curr, 0);
    int rprev = 0;
    int i = begin, j = end, iter = end - begin + 1;
    while( iter-- ){
        val[i].fleft = lprev = MIN(val[i].curr, lprev);
        rprev = ( val[j].sign ) ? MIN(rprev + 1, 0) : rprev - 1;
        val[j].fright = rprev;
        val[i].begin = begin;
        val[i].end = end;
        ++i;
        --j;
    }
}

void setVal(int n, int m)
{
    int iter = 0;
    int i = 0, j = 0, curr = 0, b = 0, x;
    for(x=N=1; m>N; x++,N<<=1);
    while(iter < m){
        x = ( i + LL(j)*n ) % m;
        if( visi[x] ){
            setInterval(b,iter-1); b = iter;
            ++i; j = curr = 0; x = (i + LL(j*n) ) % m;
        }
        visi[x] = 1;
        pos[x] = iter;
        val[iter].sign = (str[x] == 'W');
        curr += (val[iter].sign) ? 1 : -1;
        val[iter].curr = curr;
        tree[iter+N] = curr;
        ++j; ++iter;
    }
    setInterval(b,iter-1);
    for(i=N>>1,j=N; i; i>>=1,j>>=1){
        for(x = i; x < j; x++){
            tree[x] = MIN(tree[x<<1],tree[(x<<1)+1]);
        }
    }
}

void solve(int n, int m)
{
    int i;
    long long res = INF;
    for(i = 0; i < n; i++){
        ans[i] = getAns(i, a[i], n, m);
        res = MIN(res, ans[i]);
    }

    if(res == INF) printf("-1\n");
    else printf("%lld\n",res);
}

int query(int f, int s) {
    f += N; s += N;
    int res = MIN(tree[f],tree[s]);
    while(f>>1 != s>>1) {
        if(~f&1) res = MIN(res,tree[f+1]);
        if(s&1)  res = MIN(res,tree[s-1]);
        f >>= 1; s >>= 1;
    }
    return res;
}

int binarySearchR(SNode *t, int l, int r, int a)
{
    int end = r, p = l;
    int s, v;
    while(l < r){
        s = (l + r)>>1;
        if(s == end) v = t[p].fright;
        else v = query(p,s) - tree[p-1+N];
        if(a == v)
            r = s;
        else if(a > v)
            r = s - 1;
        else
            l = s + 1;
    }
    return l;
}
int binarySearchL(SNode *t, int l, int r, int a, int bias)
{
    int s;
    while(l < r){
        s = (l + r)>>1;
        if(a == bias + t[s].fleft)
            r = s;
        else if(a > bias + t[s].fleft)
            r = s - 1;
        else
            l = s + 1;
    }
    return l;
}

long long NWD(long long a, long long b){
    long long c;
    while(b){
        c = a%b;
        a = b;
        b = c;
    }
    return a;
}

long long NWW(long long a, long long b){
    return a/NWD(a,b)*b;
}

long long getAns(int i, int a, int n, int m)
{
    int x = i%m;
    int p = pos[x];
    int begin = val[p].begin;
    int end = val[p].end;
    int ds = val[end].curr;
    int ms = val[p].fright;

    if(p > begin) ms = MIN(ms, val[end].curr - val[p-1].curr + val[p-1].fleft);
    long long res = 0;
    int ix;

    if(ms >= 0) return INF;
    if(ds >= 0){
        if(a + ms > 0) return INF;
    }
    else if(a > -ms){
        int k = (a + ms - ds - 1)/(-ds);
        res += LL(k)*NWW(n,m);
        a -= k*(-ds);
    }

    if(p == begin){
        ix = binarySearchL(val, begin, end, -a, 0);
        res += LL(ix - p)*n;
    }
    else if(val[p].fright <= -a){
        ix = binarySearchR(val, p, end, -a);
        res += LL(ix - p)*n;
    }
    else{
        ix = binarySearchL(val, begin, p-1, -a, val[end].curr - val[p-1].curr);
        res += LL(end - p + 1 + ix - begin)*n;
    }

    return res + i + 1;
}