import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.NoSuchElementException;

class Main {
	
	public static void main(String[] args) {
		new Main().run();
	}
	
	
	void run() {
		solve();
	}
	
	long mod=(long)1e9+7;
	
	int MAX=2000000;
	
	void solve() {
		FastScanner sc=new FastScanner();
		PrintWriter pw=new PrintWriter(System.out);
		
		int N=sc.nextInt();
		int[] A=new int[N];
		for (int i=0;i<N;++i) {
			A[i]=sc.nextInt();
		}
		int m=26;
		ArrayDeque<Integer>[] dq=new ArrayDeque[m];
		for (int i=0;i<m;++i) dq[i]=new ArrayDeque<>();
		char[] cs=sc.next().toCharArray();
		for (int i=0;i<N;++i) {
			int num=cs[i]-'a';
			dq[num].addLast(i);
		}
		long[][] dp=new long[N+1][2];
		dp[0][0]=1;
		for (int i=0;i<N;++i) {
			for (int j=0;j<m;++j) {
				while (!dq[j].isEmpty() && dq[j].peekFirst() < i) dq[j].pollFirst();
				if (dq[j].isEmpty()) continue;
				int nxt=dq[j].peekFirst();
				if (i>0 && cs[nxt]==cs[i-1]) {
					dp[nxt+1][0]+=dp[i][1]*(A[nxt]-1)%mod;
					dp[nxt+1][1]+=dp[i][1];
				} else {
					dp[nxt+1][0]+=(dp[i][0]+dp[i][1])*(A[nxt]-1)%mod;
					dp[nxt+1][1]+=(dp[i][0]+dp[i][1])%mod;
				}
				dp[nxt+1][0]%=mod;
				dp[nxt+1][1]%=mod;
				
			}
		}
		long ans=0;
		for (int i=1;i<dp.length;++i) {
			for (int j=0;j<dp[i].length;++j) {
				ans+=dp[i][j];
				ans%=mod;
			}
		}
		System.out.println(ans);
		pw.close();
	}
	
	static void tr(Object...objects) {
		System.out.println(Arrays.deepToString(objects));
	}

}


class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;}
    public boolean hasNext() { skipUnprintable(); return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
    	return (int)nextLong();
    }
}