from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right
from itertools import permutations, combinations, groupby
from heapq import heappop, heappush
import math, sys
input = lambda: sys.stdin.readline().rstrip("\r\n")
def printl(li, sep=" "): print(sep.join(map(str, li)))
def yn(flag): print(Yes if flag else No)
_int = lambda x: int(x)-1
MOD = 998244353 #10**9+7
INF = 1<<60
Yes, No = "Yes", "No"

class FenwickTree:
    '''Reference: https://en.wikipedia.org/wiki/Fenwick_tree'''

    def __init__(self, n: int = 0) -> None:
        self._n = n
        self.data = [0] * n

    def add(self, p: int, x: int) -> None:
        assert 0 <= p < self._n

        p += 1
        while p <= self._n:
            self.data[p - 1] += x
            p += p & -p

    def sum(self, left: int, right: int) -> int:
        assert 0 <= left <= right <= self._n

        return self._sum(right) - self._sum(left)

    def _sum(self, r: int) -> int:
        s = 0
        while r > 0:
            s += self.data[r - 1]
            r -= r & -r

        return s

N = int(input())
A = list(map(int, input().split()))
X = sorted(list(set(A)))
M = len(X)
pos = {x: e for e, x in enumerate(X)}
F = FenwickTree(M)
ans = 0
for i in range(N):
    ans += F.sum(pos[A[i]]+1, M)
    F.add(pos[A[i]], 1)
print(ans)