import bisect
import copy
import decimal
import fractions
import heapq
import itertools
import math
import sys
from collections import deque,defaultdict,Counter
from functools import lru_cache,reduce
from math import gcd as Gcd
read=sys.stdin.read
readline=sys.stdin.readline
readlines=sys.stdin.readlines

N,*A=map(int,read().split())
ans=N*(N+1)//2
cur=0
while cur!=N:
    if A[cur]==0:
        cur+=1
        continue
    i=cur+1
    while i!=N and A[i]==1:
        i+=1
    ans-=(i-cur)*(i-cur+1)//2
    cur=i
print(ans)