#include <bits/stdc++.h>
using namespace std;
priority_queue<long long int, vector<long long int>, greater<long long int>> ti;
vector<long long int> p[200005], y[300005], f(500005, 0), b(500005, 0),
    r(500005, 0), a(500005, 0);
vector<pair<long long int, long long int>> t, h;
long long int vis[200005];
map<pair<long long int, long long int>, long long int> mp;
set<pair<long long int, long long int>> s;
set<long long int> st;
map<long long int, long long int> np, v;
queue<long long int> qy;
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int bpow(long long int a, long long int b) {
  long long int res = 1;
  while (b > 0) {
    if (b & 1) res = (res * a) % 998244353;
    a = (a * a) % 998244353;
    b >>= 1;
  }
  return res % 998244353;
}
void fact(long long int i) {
  f[0] = 1;
  for (long long int k = 1; k <= i; k++) {
    (f[k] = f[k - 1] * k) %= 998244353;
  }
}
long long int isprime(long long int n) {
  if (n == 1) return 0;
  for (long long int i = 2; i <= sqrt(n); i++)
    if (n % i == 0) return 0;
  return 1;
}
long long int find(long long int x) {
  if (f[x] == x)
    return x;
  else
    return f[x] = find(f[x]);
}
bool cmp(long long int i, long long int j) { return p[i].size() < p[j].size(); }
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int n;
  cin >> n;
  vector<long long int> p(1), q;
  long long int x;
  for (long long int i = 1; i <= n; i++) {
    cin >> x;
    if (x != p.back()) p.push_back(x);
  }
  n = p.size() - 1;
  q = p;
  reverse(q.begin() + 1, q.end());
  vector<vector<long long int>> dp(n + 1, vector<long long int>(n + 1, 0));
  for (long long int i = 1; i <= n; i++) {
    for (long long int j = 1; j <= n; j++) {
      if (p[i] == q[j])
        dp[i][j] = dp[i - 1][j - 1] + 1;
      else
        dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
    }
  }
  cout << n - (dp[n][n] + 1) / 2 << "\n";
}
