"""

想定解 v2

(数字,index)
を昇順ソート
転倒数を求める

"""

import sys
from sys import stdin

def bitadd(a,w,bit): #aにwを加える

    a += 1
    x = a
    while x <= (len(bit)-1):
        bit[x] += w
        x += x & (-1 * x)
 
def bitsum(a,bit): #ind 0～aまでの和を求める

    a += 1
    ret = 0
    x = a
    while x > 0:
        ret += bit[x]
        x -= x & (-1 * x)
    return ret

N = int(stdin.readline())

A = list(map(int,stdin.readline().split()))

assert 2 <= N <= 3000

B = [A[i] for i in range(N)]
B.sort()
for i in range(N):
    assert B[i] == i+1

num_ind = [] #数字、indexを入れておく
for i in range(N):
    num_ind.append( (A[i] , i) )
    
num_ind.sort()

BIT = [0] * (200100)
ans = 0

for i in range(N):
    ans += i - bitsum( num_ind[i][1] , BIT )
    bitadd( num_ind[i][1]+1 , 1 , BIT)

print (ans)