#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001



int main(){
	
	int n;
	cin>>n;
	vector<long long> a(n);
	rep(i,n)cin>>a[i];
	
	string s;
	cin>>s;
	
	vector nxt(n+1,vector<int>(26,Inf));
	vector<int> cur(26,Inf);
	for(int i=n-1;i>=0;i--){
		nxt[i] = cur;
		cur[s[i]-'a'] = i;
	}
	
	vector<mint> dp(n+1,0);
	set<char> S;
	rep(i,n){
		if(!S.count(s[i]))dp[i] = 1;
		S.insert(s[i]);
	}
	mint ans = 0;
	
	rep(i,n){
		ans += dp[i] * (a[i]);
		rep(j,26){
			if(nxt[i][j]==Inf)continue;
			if(j==s[i]-'a'){
				dp[nxt[i][j]] += dp[i];
			}
			else{
				dp[nxt[i][j]] += dp[i] * a[i];
			}
		}
	}
	
	cout<<ans.val()<<endl;
	
	
	
	return 0;
}