#include <vector>
#include <iostream>
//#include <gtest/gtest.h>

using std::vector;

long mergeInversionCount(vector<int> &B, vector<int> &C, vector<int> &D) {
	long count = 0;
	while (B.size() != 0 && C.size() != 0) {
		int b = B[0];
		int c = C[0];
		if (b <= c) {
			D.push_back(b);
			B.erase(B.begin());
		} else {
			count += B.size();
			D.push_back(c);
			C.erase(C.begin());
		}
	}
	D.insert(D.end(), B.begin(), B.end());
	D.insert(D.end(), C.begin(), C.end());
	return count;
}
long getInversionCountFromList(vector<int> &A, vector<int> &D) {
	long numberOfInversions = 0;
	if (A.size() == 1) {
		D.push_back(A[0]);
		return 0;
	}
	int m = A.size() / 2;
	vector<int> D1;
	vector<int>::const_iterator first = A.begin();
	vector<int>::const_iterator last = A.begin() + m;
	vector<int> newVec(first, last);
	numberOfInversions += getInversionCountFromList(newVec, D1);
	vector<int> D2;
	vector<int>::const_iterator ffirst = A.begin() + m;
	vector<int>::const_iterator llast = A.end();
	vector<int> newVecc(ffirst, llast);
	numberOfInversions += getInversionCountFromList(newVecc, D2);
	long mergeCount = mergeInversionCount(D1, D2, D);
	return numberOfInversions + mergeCount;
}

//TEST(InversionCount, test1) {
//	vector<int> a = { 2, 3, 9, 2, 2 };
//	vector<int> result(5);
//	ASSERT_EQ(4, getInversionCountFromList(a, result));
//}

int main() {
  int n;
  std::cin >> n;
  vector<int> a(n);
  for (size_t i = 0; i < a.size(); i++) {
    std::cin >> a[i];
  }
  vector<int> b(a.size());
  std::cout << getInversionCountFromList(a, b) << '\n';
}