#include "bits/stdc++.h" #define int long long using namespace std; using ll = long long; using P = pair; const ll INF = (1LL << 61); ll mod = 1000000007; struct mint { ll x; // typedef long long ll; mint(ll x = 0) :x((x%mod + mod) % mod) {} mint operator-() const { return mint(-x); } mint& operator+=(const mint a) { if ((x += a.x) >= mod) x -= mod; return *this; } mint& operator-=(const mint a) { if ((x += mod - a.x) >= mod) x -= mod; return *this; } mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this; } mint operator+(const mint a) const { mint res(*this); return res += a; } mint operator-(const mint a) const { mint res(*this); return res -= a; } mint operator*(const mint a) const { mint res(*this); return res *= a; } mint pow(ll t) const { if (!t) return 1; mint a = pow(t >> 1); a *= a; if (t & 1) a *= *this; return a; } // for prime mod mint inv() const { return pow(mod - 2); } mint& operator/=(const mint a) { return (*this) *= a.inv(); } mint operator/(const mint a) const { mint res(*this); return res /= a; } }; istream& operator>>(istream& is, mint& a) { return is >> a.x; } ostream& operator<<(ostream& os, const mint& a) { return os << a.x; } mint dp[100010][10]; signed main() { ios::sync_with_stdio(false); cin.tie(0); int N; cin >> N; string S; cin >> S; string T = "yukicoder"; string tmp = T; mint ans = 0; for (int i = 0; i < 10; i++) { if (i != 10) { T[i] = '?'; } for (int j = 0; j < 100010; j++)for (int k = 0; k < 10; k++)dp[j][k] = 0; dp[0][0] = 1; for (int j = 0; j < N; j++) { for (int k = 0; k < 10; k++) { dp[j + 1][k] += dp[j][k]; if (k < 9 && T[k] == S[j]) { dp[j + 1][k + 1] += dp[j][k]; } } } ans += dp[N][9]; T = tmp; } cout << ans << endl; return 0; }