import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		String[] sa = br.readLine().split(" ");
		long[] a = new long[n];
		for (int i = 0; i < n; i++) {
			a[i] = Long.parseLong(sa[i]);
		}
		br.close();

		Arrays.sort(a);
		Map<Long, Long> map = new HashMap<>();
		for (int i = 1; i < n; i++) {
			long val = 0;
			if (a[i] - 1 == a[i - 1]) {
				val++;
			}
			val += map.getOrDefault(a[i] - 1, 0L);
			map.put(a[i] + 1, val);
		}

		long ans = n;
		for (long v : map.values()) {
			ans += v;
		}
		System.out.println(ans);
	}
}