#!/usr/bin/env python3
# from typing import *

import sys
import io
import math
import collections
import decimal
import itertools
import bisect
import heapq


def input():
    return sys.stdin.readline()[:-1]


# sys.setrecursionlimit(1000000)

# _INPUT = """3
# 3 2 1

# """
# sys.stdin = io.StringIO(_INPUT)

class BIT:
    def __init__(self, n):
        self.size = n
        self.data = [0] * (n+1)
        # self.depth = n.bit_length()
    def add(self, i, x):
        while i <= self.size:
            self.data[i] += x
            i += i & -i
    def get_sum(self, i):
        s = 0
        while i > 0:
            s += self.data[i]
            i -= i & -i
        return s
    def get_rsum(self, l, r):
        """
        [l, r] の sum
        """
        return self.get_sum(r) - self.get_sum(l-1)


INF = 10**10

N = int(input())
A = list(map(lambda x: int(x)-1, input().split()))


bit = BIT(N)
v = 0
for a in reversed(A):
    v += bit.get_sum(a+1)
    bit.add(a+1, 1)
    
print(v)