from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline

N = int(input())
A = list(map(int,input().split()))

ans = N*(N+1)//2
for g,r in groupby(A):
    if g==1:
        n = len(list(r))
        ans -= n*(n+1)//2
print(ans)