#include <bits/stdc++.h>
#include <atcoder/string>
#include <atcoder/modint>
using namespace std;
using Modint = atcoder::modint1000000007;


Modint solve(string s){
    auto sa = atcoder::suffix_array(s);
    Modint ans = s.size() * (s.size() + 1) / 2;
    for(auto i : atcoder::lcp_array(s, sa)) ans -= i;
    return ans;
}
int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int N;
    cin >> N;
    vector<int> A(N);
    for(int& a : A) cin >> a;
    if(accumulate(A.begin(), A.end(), 0LL) >= 2e7) abort();
    string S;
    for(int i = 0; i < N; i++){
        char c;
        cin >> c;
        S += string(A[i], c);
    }
    cout << solve(S).val() << endl;
}