#include<cstdio>
#include<cstring>
#include<atcoder/modint>
using namespace atcoder;
using Mint = modint1000000007;
int main(){
    int N;
    scanf("%d", &N);
    int A[N];
    for(int i = 0; i < N; ++i) scanf("%d", A + i);
    int last[26];
    memset(last,0,sizeof last);
    Mint dp_cum[N+1];
    Mint dp_max[N+1];
    dp_cum[0] = Mint::raw(0);
    dp_max[0] = Mint::raw(1);
    scanf("\n");
    for (int i = 0; i < N; i++)
    {
        char S;
        scanf("%c", &S);
        S -= 'a';
        dp_max[i+1] = dp_cum[i] - dp_cum[last[S]] + dp_max[last[S]];
        dp_cum[i+1] = dp_cum[i] + dp_max[i+1]*Mint::raw(A[i]);
        last[S] = i+1;
    }
    printf("%u\n", dp_cum[N].val());
}