import sys
input = sys.stdin.readline

N = int(input())
A = list(map(int, input().split()))
ans = N*(N+1)//2
now = 0

for Ai in A:
    if Ai==1:
        now += 1
    else:
        ans -= now*(now+1)//2
        now = 0

ans -= now*(now+1)//2
print(ans)