#include <bits/stdc++.h>
using namespace std;
template <class T>
T power(T N, T P) {
  return (P == 0) ? 1 : N * power(N, P - 1);
}
template <class T>
T gcd(T a, T b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
template <class T1>
void deb(T1 e1) {
  cout << e1 << endl;
}
template <class T1, class T2>
void deb(T1 e1, T2 e2) {
  cout << e1 << " " << e2 << endl;
}
template <class T1, class T2, class T3>
void deb(T1 e1, T2 e2, T3 e3) {
  cout << e1 << " " << e2 << " " << e3 << endl;
}
template <class T1, class T2, class T3, class T4>
void deb(T1 e1, T2 e2, T3 e3, T4 e4) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << endl;
}
template <class T1, class T2, class T3, class T4, class T5>
void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << " " << e5 << endl;
}
template <class T1, class T2, class T3, class T4, class T5, class T6>
void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5, T6 e6) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << " " << e5 << " " << e6
       << endl;
}
long long int on(long long int n, long long int pos) {
  return n = n | (1 << pos);
}
bool check(int n, int pos) { return (bool)(n & (1 << pos)); }
const int N = 500 + 5;
int dp[N][N], a[N];
int rec(int b, int e) {
  if (b >= e) return 1;
  int &ret = dp[b][e];
  if (ret != -1) return ret;
  ret = INT_MAX;
  if (a[b] == a[e]) ret = rec(b + 1, e - 1);
  for (int i = b; i <= e; i++) {
    ret = min(ret, rec(b, i) + rec(i + 1, e));
  }
  return ret;
}
int main() {
  int n;
  while (scanf("%d", &n) != EOF) {
    for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
    memset(dp, -1, sizeof(dp));
    printf("%d\n", rec(1, n));
  }
  return 0;
}
