#include <bits/stdc++.h>
using namespace std;
int n, i, j, m, ans, p = 51123987, i1, i2, i3, la[3], nt[151][3],
                     f[151][53][53][53];
char s[201];
int main() {
  scanf("%d", &n);
  scanf("%s", s + 1);
  for (i = n; i; i--) {
    la[s[i] - 'a'] = i;
    for (j = 0; j < 3; j++) nt[i][j] = la[j];
  }
  f[1][0][0][0] = 1;
  m = (n + 2) / 3;
  for (i = 1; i <= n; i++)
    for (i1 = 0; i1 <= m; i1++)
      for (i2 = 0; i2 <= m; i2++)
        for (i3 = 0; i3 <= m; i3++) {
          if (i1 + i2 + i3 == n && abs(i1 - i2) <= 1 && abs(i1 - i3) <= 1 &&
              abs(i2 - i3) <= 1)
            ans = (ans + f[i][i1][i2][i3]) % p;
          if (nt[i][0]) (f[nt[i][0]][i1 + 1][i2][i3] += f[i][i1][i2][i3]) %= p;
          if (nt[i][1]) (f[nt[i][1]][i1][i2 + 1][i3] += f[i][i1][i2][i3]) %= p;
          if (nt[i][2]) (f[nt[i][2]][i1][i2][i3 + 1] += f[i][i1][i2][i3]) %= p;
        }
  printf("%d", ans);
}
