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#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <deque>
#define INF 1000000000000000000LL
using namespace std;
//#define TEST
//#define TEST2


int n, m;
int *r;
char *s;
int **D;
long long *game;

void init();
int main()
{
	ios_base::sync_with_stdio(false);
	
	init();
	
	int gcd, nn=n, mm=m, tt;
	while(mm>0) {
		tt = mm;
		mm = nn%mm;
		nn = tt;
	}
	gcd = nn;
	
#ifdef TEST
	cout << "n: " << n << endl << "m: " << m << endl << "gcd: " << gcd << endl;
#endif
#ifdef TEST2
	cout << "n: " << n << endl << "m: " << m << endl << "gcd: " << gcd << endl;
#endif
	
	deque<char> Q;
	for( int k=0 ; k<gcd ; k++ ) {
		Q.push_back( s[k] );
		
		int pos = (k+n)%m;		
		int i=1;
		while( pos!=k ) {
			
			Q.push_back( s[pos] );	
			
			pos = (pos+n)%m;
			
			i++;
		}
#ifdef TEST
		cout << "Q:\tdla k="<<k<<endl;
		for( int i=0 ; i<Q.size() ; i++ )
			cout << Q[i] << " ";
		cout << endl;
#endif
		
		
		int last=0;
		int cycle=0;
		deque<int> W;
		for( int i=0 ; i<Q.size() ; i++ ) {
			if( Q[i]=='W' )
				cycle++;
			else
				cycle--;
			if( cycle<last ) {
				last--;
				W.push_back(i);
			}
		}
		
#ifdef TEST
		cout << "cycle: " << cycle << endl;
#endif
		
		long long interval;
		int kara=0;
		int j=k;
		do {
			for( int i=j ; i<n ; i+=m ) {
#ifdef TEST
	cout << "i: " << i << endl;
		for( int e=0 ; e<W.size() ; e++ )
			cout << W[e] << " ";
		cout << endl;
#endif
				if( r[i] <= W.size() ) {
					game[i] = W[ r[i]-1 ] + 1 + kara;
				} else if( cycle>=0 ) {
					game[i] = INF;
				} else {
					game[i] = 0;
					interval = r[i]-W.size();
					interval = (interval-1)/(-cycle) + 1;//zaokraglenie w gore
					game[i] += (m/gcd) * interval + W[ r[i]-interval*(-cycle) -1 ] + 1 + kara;
#ifdef TEST
					if( i==4 )
						cout << "interval: " << interval << " r[i] "<<r[i] <<" W.size " <<W.size()<<endl;
#endif
				}
#ifdef TEST
				cout << "game[" << i << "]: " << game[i] << endl;
#endif
			}
			
			j -= n;
			j %= m;
			kara++;
			if( j<0 ) j += m;
			
			if( s[j]=='W' && W.size()>0 ) {
				W.pop_front();
			} else {
				W.push_front(-kara);
			}
			if( W.size()>0 && W.back()+kara >= m/gcd )
				W.pop_back();
						
			
		} while( j!=k );

		while( !Q.empty() )
			Q.pop_back();
	}
	
	
	long long minimal = INF;
	
	for( int i=0 ; i<n ; i++ ) {
		if( game[i]!=INF && minimal > i + 1 + (game[i]-1)*n )
			minimal = i + 1 + (game[i]-1)*n;
	}	
	
	if( minimal==INF ) cout << "-1" << endl;
	else cout << minimal << endl;
	
	
	return 0;
}


void init() {
	cin >> n;
	r = new int [n];
	for( int i=0 ; i<n ; i++ )
		cin >> r[i];
	cin >> m;
	s = new char[m+1];
	cin >> s;
	game = new long long [n];
}