n=int(input())
a=list(map(int,input().split()))
c=0
l=0
while l<n-1:
  if a[l]==0:
    l+=1
    continue
  r=l
  while r+1<n-1 and a[r+1]!=a[r]:
    r+=1
  for i in range(l,r+1,2):
    c+=r-i+1
  l=r+1
print(c)