import sys
input = sys.stdin.readline
def iinput(): return int(input())
def sinput(): return input().rstrip()
def i0input(): return int(input()) - 1
def linput(): return list(input().split())
def liinput(): return list(map(int, input().split()))
def miinput(): return map(int, input().split())
def li0input(): return list(map(lambda x: int(x) - 1, input().split()))
def mi0input(): return map(lambda x: int(x) - 1, input().split())
INF = 10**20
MOD = 1000000007

N = iinput()
A = liinput()

ans = 0
tmp = []
for i, a in enumerate(A):
    if tmp == []:
        if a == 1:
            tmp.append(a)
    else:
        if a != tmp[-1]:
            tmp.append(a)
        else:
            if tmp[0] == 1:
                l = len(tmp)
                ll = l // 2
                ans += ll * (ll + 1) + (l % 2) * (ll + 1)
            if a == 0:
                tmp = []
            else:
                tmp = [a]
l = len(tmp)
ll = l // 2
ans += ll * (ll + 1)
print(ans)