#include <cstdio>

template <typename T> T read();
template <typename T> void write(T, char);
template <typename T> T max(T, T);

const int MAXN = 210;

int n;
int a[MAXN];
int color[MAXN], nums[MAXN], cnt;
int f[MAXN][MAXN];

int main() {
  freopen("eliminate.in", "r", stdin);
  freopen("eliminate.out", "w", stdout);
  n = read<int>();
  for (int i = 1; i <= n; ++i) {
    a[i] = read<int>();
    if (a[i] != a[i - 1]) {
      color[++cnt] = a[i];
      nums[cnt] = 1;
    } else {
      nums[cnt]++;
    }
  }

  for (int i = 1; i <= cnt; ++i) f[i][i] = nums[i] * nums[i];

  for (int len = 2; len <= cnt; ++len) {
    for (int l = 1; l <= cnt - len + 1; ++l) {
      int r = l + len - 1;
      if (color[l] == color[r]) f[l][r] = f[l + 1][r - 1] + (nums[l] + nums[r]) * (nums[l] + nums[r]);
      for (int k = l; k < r; ++k) {
        f[l][r] = max(f[l][r], f[l][k] + f[k + 1][r]);
      }
    }
  }

  write(f[1][cnt], '\n');
}

template <typename T> T max(T x, T y) {
  return x > y ? x : y;
}

#define isdigit(ch) (ch >= '0' && ch <= '9')
template <typename T> T read() {
  T res = 0, f = 1;
  char ch = getchar();
  for (; !isdigit(ch); ch = getchar())
    if (ch == '-') f = -1;
  for (; isdigit(ch); ch = getchar()) res = (res << 3) + (res << 1) + (ch ^ 48);
  return res * f;
}

template <typename T> void write(T x, char ed) {
  if (x < 0) x = -x, putchar('-');
  static int sta[sizeof(T) << 2], top = 0;
  do {
    sta[++top] = x % 10;
    x /= 10;
  } while (x);
  while (top) {
    putchar(sta[top--] ^ 48);
  }
  putchar(ed);
}