import bisect

class BIT:
    # 0-idx
    # (i, j)は両端点含む。
    def __init__(self, n):
        self.n = n
        self.a = [0] * (n + 1)

    def add(self, i, x):
        i += 1
        while i <= self.n:
            self.a[i] += x
            i += i & (-i)

    def sum_sub(self, i):
        i += 1
        s = 0
        while i > 0:
            s += self.a[i]
            i -= i & (-i)
        return s
    
    def sum(self, i, j):
        return self.sum_sub(j) - self.sum_sub(i - 1)

    # a[0]+a[1]+...+a[i] >= x となる最小のiを返す (a[k] >= 0が前提)
    def lower_bound(self, x):
        if x <= 0:
            return 0
        i = 0
        r = 1
        while r < self.n:
            r <<= 1
        length = r
        while length > 0:
            if i + length <= self.n and self.a[i + length] < x:
                x -= self.a[i + length]
                i += length
            length >>= 1
        return i

N=int(input())
A=list(map(int, input().split()))
bit=BIT(N)
As = sorted(set(A))
ans = 0
for i in range(N):
    idx = bisect.bisect_left(As, A[i])
    if idx + 1 < N:
        ans += bit.sum(idx+1, N-1)
    bit.add(idx, 1)

print(ans)