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#include <bits/stdc++.h>
using namespace std;
struct debugger {
  template <typename T>
  debugger& operator,(const T& v) {
    cerr << v << " ";
    return *this;
  }
} dbg;
inline long long gcd(long long a, long long b) {
  a = ((a) < 0 ? -(a) : (a));
  b = ((b) < 0 ? -(b) : (b));
  while (b) {
    a = a % b;
    swap(a, b);
  }
  return a;
}
long long ext_gcd(long long A, long long B, long long* X, long long* Y) {
  long long x2, y2, x1, y1, x, y, r2, r1, q, r;
  x2 = 1;
  y2 = 0;
  x1 = 0;
  y1 = 1;
  for (r2 = A, r1 = B; r1 != 0;
       r2 = r1, r1 = r, x2 = x1, y2 = y1, x1 = x, y1 = y) {
    q = r2 / r1;
    r = r2 % r1;
    x = x2 - (q * x1);
    y = y2 - (q * y1);
  }
  *X = x2;
  *Y = y2;
  return r2;
}
inline long long modInv(long long a, long long m) {
  long long x, y;
  ext_gcd(a, m, &x, &y);
  x %= m;
  if (x < 0) x += m;
  return x;
}
inline long long power(long long a, long long p) {
  long long res = 1, x = a;
  while (p) {
    if (p & 1) res = (res * x);
    x = (x * x);
    p >>= 1;
  }
  return res;
}
inline long long bigmod(long long a, long long p, long long m) {
  long long res = 1 % m, x = a % m;
  while (p) {
    if (p & 1) res = (res * x) % m;
    x = (x * x) % m;
    p >>= 1;
  }
  return res;
}
const long long inf = 2147383647;
const long long mod = 1000000007;
const double pi = 2 * acos(0.0);
const double eps = 1e-9;
int n, ans, oc[5005][30];
char s[5005];
int dp[2][5005];
int main() {
  memset(oc, -1, sizeof(oc));
  cin >> n >> s;
  for (long long i = (n - 1); i >= (0); --i) {
    for (int j = 0; j < 26; j++) {
      oc[i][j] = oc[i + 1][j];
    }
    oc[i][s[i] - 'a'] = i;
  }
  for (long long i = (0); i <= (n - 1); ++i) dp[0][i] = dp[1][i] = 1;
  for (long long i = (n - 2); i >= (0); --i) {
    for (long long j = (n - 1); j >= (0); --j) {
      dp[0][j] = 0;
      dp[0][j] = (dp[0][j + 1] + dp[1][j]) % mod;
      if (oc[j + 1][s[j] - 'a'] != -1) {
        dp[0][j] = (dp[0][j] - dp[1][oc[j + 1][s[j] - 'a']]) % mod;
        if (dp[0][j] >= mod) dp[0][j] -= mod;
        if (dp[0][j] < 0) dp[0][j] += mod;
        ;
      }
    }
    for (long long j = (0); j <= (n - 1); ++j) dp[1][j] = dp[0][j];
  }
  for (int i = 0; i < 26; i++) {
    if (oc[0][i] != -1) ans = (ans + dp[0][oc[0][i]]) % mod;
  }
  cout << ans << "\n";
  return 0;
}
