import java.util.Scanner;

public class No1505 {
	
	private static long nCr(int n)
	{
		if (n < 2 || n <= 0) {
			return 0L;
		}
		return (long)n * (long)(n-1) / 2L;
	}

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int j = -1;
		long cnt = nCr(N) + N;
		int i = 0;
		for (; i < N; i++) {
			if (scan.nextInt() == 1) {
				if (j < 0) {
					j = i;
				}
			} else {
				if (j >= 0) {
					cnt -= nCr(i-j) + (long)(i-j);
				}
				j = -1;
			}
		}
		if (j >= 0) {
			cnt -= nCr(i-j) + (long)(i-j);
		}
		scan.close();
		System.out.println(cnt);
	}
}