#include <bits/stdc++.h>
using namespace std;

static const int MOD = 1000000007;

// safe addition
inline int add(int a, int b) {
    a += b;
    if (a >= MOD) a -= MOD;
    return a;
}

// safe subtraction
inline int sub(int a, int b) {
    a -= b;
    if (a < 0) a += MOD;
    return a;
}

// safe multiplication
inline long long mul(long long a, long long b) {
    return (a * b) % MOD;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N;
    cin >> N;
    vector<long long> A(N);
    for(int i = 0; i < N; i++){
        cin >> A[i];
    }
    string S;
    cin >> S;

    // dp = number of distinct subsequences (including empty) so far
    int dp = 1;
    // last[c] = dp-value just before we last processed character c
    vector<int> last(26, 0);

    for(int i = 0; i < N; i++){
        int c = S[i] - 'a';
        long long L = A[i] % MOD;

        int dp_before = dp;
        int last_dp = last[c];  // dp at position just before this run

        // inc0 = dp_before - last_dp
        int inc0 = sub(dp_before, last_dp);

        // dp = dp_before + L * inc0
        dp = add(dp_before, (int)mul(L, inc0));

        // update last[c] = dp_{L-1} = dp_before + (L-1)*inc0
        long long L1 = (A[i] - 1) % MOD;
        if (L1 < 0) L1 += MOD;
        last[c] = add(dp_before, (int)mul(L1, inc0));
    }

    // subtract the empty subsequence
    int ans = sub(dp, 1);
    cout << ans << "\n";
    return 0;
}