n = int(input())
arr = list( map(int, input().split()) )


ans = [0]
def merge_sort(arr):
    if len(arr) <= 1:
        return arr

    n = len(arr)
    mid = (n-1) // 2
    arr1, arr2 = arr[:mid+1], arr[mid+1:]
    merge_sort(arr1)
    merge_sort(arr2)

    for val in arr1:
        l, r = 0, len(arr2)-1
        pos = -1
        while l <= r:
            m = l + (r-l) // 2
            if arr2[m] < val:
                pos = m
                l = m + 1
            else:
                r = m - 1

        if pos != -1:
            ans[0] += pos+1

    arr.sort()
    return arr

merge_sort(arr)
print(ans[0])