#include <iostream>
#include <vector>

using namespace std;

long Count(vector<long> &A){

	if (A.size() <= 1)
		return 0;

	vector<long> A1, A2;

	for (long i=0;i<A.size()/2;i++)
		A1.push_back(A[i]);
	for (long i=A.size()/2;i<A.size();i++)
		A2.push_back(A[i]);

	long m = 0, c = Count(A1) + Count(A2);
	
	A.clear();
	for (long i=0;i<A1.size();i++) {
		for (;(m<A2.size())&&(A2[m]<A1[i]);m++) {
			A.push_back(A2[m]);
			c+= A1.size()-i;
		}
		A.push_back(A1[i]);
	}

	for (;m<A2.size();m++)
		A.push_back(A2[m]);

	return c;
}

int main(){
	
	long N, tmp;

	cin >> N;
	vector<long> A(N);

	for (long i=0;i<N;i++)
		cin >> A[i];

	cout << Count(A);
}