#include <bits/stdc++.h>
using namespace std;
const int modulo = 51123987;
int f[151][52][52][4], g[151][52][52][4];
char str[151];
int main() {
  int n;
  scanf("%d%s", &n, str);
  memset(f, 0, sizeof(f));
  f[0][0][0][3] = 1;
  int upper = n / 3 + 1;
  for (int i = 0; i < n; i++) {
    memset(g, 0, sizeof(g));
    for (int j = 0; j <= n; j++)
      for (int c1 = 0; c1 <= i && c1 <= upper; c1++)
        for (int c2 = 0; c1 + c2 <= i && c2 <= upper; c2++)
          for (int k = 0; k < 4; k++) {
            if (f[j][c1][c2][k] == 0) continue;
            if (k < 3) {
              if (k == 0 && c1 < upper)
                g[j][c1 + 1][c2][k] =
                    (g[j][c1 + 1][c2][k] + f[j][c1][c2][k]) % modulo;
              if (k == 1 && c2 < upper)
                g[j][c1][c2 + 1][k] =
                    (g[j][c1][c2 + 1][k] + f[j][c1][c2][k]) % modulo;
              if (k == 2)
                g[j][c1][c2][k] = (g[j][c1][c2][k] + f[j][c1][c2][k]) % modulo;
            }
            for (int t = 0; t < 3; t++)
              if (t != k) {
                int p = j;
                while (p < n && str[p] != 'a' + t) p++;
                if (p >= n) continue;
                if (t == 0 && c1 < upper)
                  g[p + 1][c1 + 1][c2][t] =
                      (g[p + 1][c1 + 1][c2][t] + f[j][c1][c2][k]) % modulo;
                if (t == 1 && c2 < upper)
                  g[p + 1][c1][c2 + 1][t] =
                      (g[p + 1][c1][c2 + 1][t] + f[j][c1][c2][k]) % modulo;
                if (t == 2)
                  g[p + 1][c1][c2][t] =
                      (g[p + 1][c1][c2][t] + f[j][c1][c2][k]) % modulo;
              }
          }
    memcpy(f, g, sizeof(g));
  }
  int ans = 0;
  for (int i = 0; i <= n; i++)
    for (int c1 = 0; c1 <= n && c1 <= upper; c1++)
      for (int c2 = 0; c1 + c2 <= n && c2 <= upper; c2++)
        for (int k = 0; k < 3; k++) {
          if (f[i][c1][c2][k] == 0) continue;
          int c3 = n - c1 - c2;
          if (abs(c1 - c2) <= 1 && abs(c1 - c3) <= 1 && abs(c2 - c3) <= 1)
            ans = (ans + f[i][c1][c2][k]) % modulo;
        }
  printf("%d\n", ans);
  return 0;
}
