#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define all(x) x.begin(),x.end()
#define ar array
#define sz(x) ((int)x.size())
template <class T,class S> inline bool chmin(T &a,const S &b) {return (a> b? a= b, 1: 0);}
template <class T,class S> inline bool chmax(T &a,const S &b) {return (a< b? a= b, 1: 0);}
const int mod = 1e9 + 7, mxn = 2e5 + 5;
int main(){
    ios_base::sync_with_stdio(false),cin.tie(0);
    int n;
    cin >> n;
    vector <int> arr(n);
    for(auto &ele: arr) cin >> ele;
    string s;
    cin >> s;
    
    ll ans = 1;
    map <char, int> dp;
    for(int i = 0;i < n;i++){
        ll tmp = ans;
        ans = (arr[i] + 1) * ans - arr[i] * dp[s[i]];
        ans %= mod;
        dp[s[i]] = arr[i] * tmp - (arr[i] - 1) * dp[s[i]];
        dp[s[i]] %= mod;
    }
    // 2 2
    // ab -> aabb  8

    --ans;

    cout << ans << "\n";

    return 0;
}