SENTINEL = 2000000000

def merge(A,n,left,mid,right):
  cnt = 0
  n1 = mid - left
  n2 = right - mid
  L = []
  R = []
  for i in range(n1):
    L.append(A[left+i])
  for j in range(n2):
    R.append(A[mid+j])
  L.append(SENTINEL)
  R.append(SENTINEL)
  i = j = 0
  for k in range(left,right):
    if L[i] <= R[j]:
      A[k] = L[i]
      i += 1
    else:
      A[k] = R[j]
      j += 1
      cnt += n1 -i

  return cnt

def mergeSort(A,n,left,right):
  if left + 1 < right:
    mid = (left + right) // 2
    v1 = mergeSort(A,n,left,mid)
    v2 = mergeSort(A,n,mid,right)
    v3 = merge(A,n,left,mid,right)
    return v1 + v2 + v3
  else:
    return 0

n = int(input())
a = list(map(int,input().split()))
print(mergeSort(a,n,0,n))

#example input
#5
#3 5 2 1 4
#
#output
#6