#include <bits/stdc++.h>
using namespace std;
const int N = 150 + 5, p = 51123987;
char s[N];
int f[N][(N + 2) / 3][(N + 2) / 3][(N + 2) / 3], nxt[N][3], n, ans;
int main() {
  scanf("%d%s", &n, s + 1);
  nxt[n + 1][0] = nxt[n + 1][1] = nxt[n + 1][2] = n + 1;
  for (int i = n; i >= 1; i--) {
    nxt[i][0] = nxt[i + 1][0];
    nxt[i][1] = nxt[i + 1][1];
    nxt[i][2] = nxt[i + 1][2];
    if (s[i] == 'a') nxt[i][0] = i;
    if (s[i] == 'b') nxt[i][1] = i;
    if (s[i] == 'c') nxt[i][2] = i;
  }
  f[1][0][0][0] = 1;
  for (int i = 1; i <= n; i++)
    for (int a = 0; a <= (n + 2) / 3; a++)
      for (int b = 0; b <= (n + 2) / 3; b++)
        for (int c = 0; c <= (n + 2) / 3; c++) {
          if (a + b + c == n && abs(a - b) <= 1 && abs(a - c) <= 1 &&
              abs(b - c) <= 1)
            ans = (ans + f[i][a][b][c]) % p;
          f[nxt[i][0]][a + 1][b][c] =
              (f[nxt[i][0]][a + 1][b][c] + f[i][a][b][c]) % p;
          f[nxt[i][1]][a][b + 1][c] =
              (f[nxt[i][1]][a][b + 1][c] + f[i][a][b][c]) % p;
          f[nxt[i][2]][a][b][c + 1] =
              (f[nxt[i][2]][a][b][c + 1] + f[i][a][b][c]) % p;
        }
  printf("%d\n", ans);
  return 0;
}
