#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,n) for(int i = 0;i < (n);i++)
int mod = 1e9+7;
int main(){
  int n;
  cin >> n;
  vector<ll> A(n);
  rep(i,n) cin >> A[i];
  string s;
  cin >> s;
  s = 'x' + s;
  vector<int> S(++n);
  rep(i,n) S[i] = s[i] - 'a';
  int next_pos[n+1][26];
  rep(i,26) next_pos[n][i] = -1;
  ll dp[n] =  {0};

  for(int i = n-1;i >= 0;i--){
    dp[i] = 1;
    rep(j,26){
      if(i < n-1 && S[i+1] == j)next_pos[i][j] = i+1;
      else next_pos[i][j] = next_pos[i+1][j];
      if(next_pos[i][j] == -1)continue;
      dp[i] += dp[next_pos[i][j]];
      dp[i] %= mod;
    }
    ll sum = dp[i] - 1;
    if(next_pos[i][S[i]] != -1)sum -= dp[next_pos[i][S[i]]];
    sum += mod;
    sum %= mod;
    if(i > 0){
      dp[i] = dp[i] + (sum+1)*(A[i-1]-1);
      dp[i]%= mod;
    }

  }
  dp[0]--;
  cout << dp[0] << endl;
  return 0;
}