#include <iostream>

using namespace std;

#define N 100010
typedef long long LL;
int arr[N];
int tmp[N];

LL merge_sort(int arr[],int l,int r) {
	if (l >= r) {
		return 0;
	}
	int mid = r + l >> 1;
	int k = 0; int i = l; int j = mid + 1;
	LL sum = 0;
	sum += merge_sort(arr, l, mid) + merge_sort(arr, mid + 1, r);
	while (i <= mid && j <= r) {
		if (arr[i] <= arr[j])tmp[k++] = arr[i++];
		else {
			sum += mid - i + 1;
			tmp[k++] = arr[j++];
		}
	}
	while(i <= mid)tmp[k++] = arr[i++];
	while(j <= r)tmp[k++] = arr[j++];
	for (i = l, j = 0; i <= r; i++, j++)arr[i] = tmp[j];
	return sum;
}
int main() {

	int n;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> arr[i];
	}
	cout << merge_sort(arr,0,n-1) << endl;
	system("pause");

	return 0;
}