#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

#include <atcoder/modint>
using mint = atcoder::modint1000000007;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n;
  string s;
  cin >> n >> s;
  mint ans = 0;
  rep(x, 10) {
    string t = "yukicoder";
    if (x < t.size()) t[x] = '?';
    vector<mint> dp(t.size() + 1, 0);
    dp[0] = 1;
    rep(i, n) {
      vector<mint> ndp(t.size() + 1, 0);
      rep(j, t.size()) {
        ndp[j] += dp[j];
        if (t[j] == s[i]) ndp[j + 1] += dp[j];
      }
      swap(dp, ndp);
    }
    ans += dp[t.size()];
  }
  cout << ans.val() << '\n';
  return 0;
}