package main

import . "fmt"
import . "os"
import bf "bufio"

func main() {
	rd:=bf.NewReader(Stdin)
	var n int
	Fscan(rd,&n)
	var s,c int64
	s = int64(n)*int64(n+1)/2
	for i:=0;i<n;i++ {
		var a int
		Fscan(rd,&a)
		if a==0 {
			s-=c*(c+1)/2
			c=0	
		} else {
			c++
		}
	}
	s-=c*(c+1)/2
	Println(s)
}