3 1 2 5 4

3

count = [0]
def merge_sort(arr):
    if len(arr) <= 1:
        return arr
    mid = len(arr) // 2
    left = merge_sort(arr[:mid])
    right = merge_sort(arr[mid:])
    return merge(left, right)
def merge(a, b):
    result = []
    i = j = 0
    while i < len(a) and j < len(b):
        if a[i] <= b[j]:
            result.append(a[i])
            i += 1
        else:
            count[0] += len(a) - i
            result.append(b[j])
            j += 1
    return result + a[i:] + b[j:]

nums = list(map(int, input().split()))
merge_sort(nums)
print(count[0])