#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using mint = modint1000000007;
const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	vector<int>a(n);
	rep(i, n)cin >> a[i];
	string s; cin >> s;
	vector<mint>dp(s.size() + 1), sumdp(dp.size() + 1);
	dp[0] = 1;
	sumdp[1] = dp[0];
	vector<int>idx(26);
	rep(i, s.size()) {
		int c = s[i] - 'a';
		dp[i + 1] = dp[idx[c]] + sumdp[i + 1] - sumdp[idx[c] + 1];
		sumdp[i + 2] = sumdp[i + 1] + dp[i + 1] * a[i];
		idx[c] = i + 1;
		//cout << dp[i + 1].val() << " " << sumdp[i + 2].val() << endl;
	}
	mint ans = sumdp.back() - 1;
	cout << ans.val() << endl;
	return 0;
}