import java.util.Scanner;

public class No1505 {
	
	private static int nCr(int n, int r)
	{
		if (n < r) {
			return 0;
		}
	    return fact(n) / (fact(r) *
	                  fact(n - r));
	}
	 
	// Returns factorial of n
	private static int fact(int n)
	{
	    int res = 1;
	    for (int i = 2; i <= n; i++)
	        res = res * i;
	    return res;
	}

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int j = -1;
		int cnt = nCr(N, 2) + 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, 2) + i-j;
				}
				j = -1;
			}
		}
		if (j >= 0) {
			cnt -= nCr(i-j, 2) + i-j;
		}
		scan.close();
		System.out.println(cnt);
	}

}