#include <iostream>
#include <vector>
#include <queue>
#include <unordered_map>
using namespace std;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int n;
	if (!(cin >> n)) return 0;
	vector<int> a(n);
	for (int i = 0; i < n; ++i) cin >> a[i];
	
	// next[i] = i 鍙充晶绗竴涓笌 a[i] 浜害鐩稿悓鐨勪綅缃紱涓嶅瓨鍦ㄥ垯涓?-1
	vector<int> next(n, -1);
	unordered_map<int, int> last; // 璁板綍姣忕浜害鏈€杩戯紙鏈€鍙筹級鐨勫嚭鐜颁綅缃?
	last.reserve(n * 2);
	
	for (int i = n - 1; i >= 0; --i) {
		if (last.count(a[i])) next[i] = last[a[i]];
		last[a[i]] = i;
	}
	
	// BFS
	vector<int> dist(n, -1);
	queue<int> q;
	dist[0] = 0;
	q.push(0);
	
	while (!q.empty()) {
		int u = q.front();
		q.pop();
		if (u == n - 1) break;
		
		int d = dist[u];
		
		// 鍚戝乏
		if (u - 1 >= 0 && dist[u - 1] == -1) {
			dist[u - 1] = d + 1;
			q.push(u - 1);
		}
		// 鍚戝彸
		if (u + 1 < n && dist[u + 1] == -1) {
			dist[u + 1] = d + 1;
			q.push(u + 1);
		}
		// 鐬Щ
		if (next[u] != -1 && dist[next[u]] == -1) {
			dist[next[u]] = d + 1;
			q.push(next[u]);
		}
	}
	
	cout << dist[n - 1] << '&#92;n';
	return 0;
}