#include <bits/stdc++.h>
using namespace std;
const int N = 200020;
string s;
stack<char> st;
string temp;
int n;
int save[155][53][53][53];
int nxt[155][4];
int main() {
  cin >> n >> s;
  for (int i = 0; i < s.length(); i++) {
    if (st.empty())
      st.push(s[i]);
    else {
      if (st.top() == s[i])
        continue;
      else
        st.push(s[i]);
    }
  }
  while (!st.empty()) {
    temp += st.top();
    st.pop();
  }
  reverse(temp.begin(), temp.end());
  memset(nxt, -1, sizeof(nxt));
  for (int i = 0; i < temp.length(); i++) {
    for (int j = i; j < temp.length(); j++) {
      if (temp[j] == 'a' && nxt[i][0] == -1) nxt[i][0] = j;
      if (temp[j] == 'b' && nxt[i][1] == -1) nxt[i][1] = j;
      if (temp[j] == 'c' && nxt[i][2] == -1) nxt[i][2] = j;
      if (nxt[i][0] != -1 && nxt[i][1] != -1 && nxt[i][2] != -1) break;
    }
  }
  save[0][0][0][0] = 1;
  int m = n / 3 + 1;
  int ans = 0;
  for (int i = 1; i <= temp.length(); i++) {
    for (int a = 0; a <= m; a++) {
      for (int b = 0; b <= m; b++) {
        for (int c = 0; c <= m; c++) {
          if (save[i - 1][a][b][c] == 0) continue;
          if (a + b + c == n && abs(a - b) <= 1 && abs(b - c) <= 1 &&
              abs(a - c) <= 1) {
            ans += save[i - 1][a][b][c];
            if (ans >= 51123987) ans -= 51123987;
          }
          int k = nxt[i - 1][0];
          if (k != -1) {
            save[k][a + 1][b][c] += save[i - 1][a][b][c];
            if (save[k][a + 1][b][c] >= 51123987)
              save[k][a + 1][b][c] -= 51123987;
          }
          k = nxt[i - 1][1];
          if (k != -1) {
            save[k][a][b + 1][c] += save[i - 1][a][b][c];
            if (save[k][a][b + 1][c] >= 51123987)
              save[k][a][b + 1][c] -= 51123987;
          }
          k = nxt[i - 1][2];
          if (k != -1) {
            save[k][a][b][c + 1] += save[i - 1][a][b][c];
            if (save[k][a][b][c + 1] >= 51123987)
              save[k][a][b][c + 1] -= 51123987;
          }
        }
      }
    }
  }
  cout << ans << endl;
  return 0;
}
