def get_input():
    N = int(input())
    numbers = [int(i) for i in input().split()]
    return N, numbers


def DPsolve(N, numbers):
    count = 0
    dp = [[1 for i in range(len(numbers))] for j in range(len(numbers))]
    for i in range(N):
        for j in range(N-i):
            if j == 0:
                dp[i][j] = numbers[i]
            else:
                dp[i][j] = dp[i][j-1] + numbers[i+j]
            if dp[i][j] == 0:
                count += 1
    return dp, count

if __name__ == '__main__':
    N, numbers = get_input()
    dp, count = DPsolve(N, numbers)
    print(count)