package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func g(n int) int {
	return n * (n + 1) / 2
}

func main() {
	var sc = bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Scan()
	N, _ := strconv.Atoi(sc.Text())
	A := make([]bool, N)
	for i := 0; i < N; i++ {
		sc.Scan()
		A[i] = sc.Text() == "1"
	}

	count := g(N)

	l := 0
	for _, b := range A {
		if b {
			l++
		} else if l > 0 {
			count -= g(l)
			l = 0
		}
	}
	if l > 0 {
		count -= g(l)
	}

	fmt.Println(count)
}