#include <stdio.h>

void add_BIT(int N, int BIT[], int i, int k)
{
	while (i <= N) {
		BIT[i] += k;
		i += (i & -i);
	}
}

long long sum_BIT(int BIT[], int r)
{
	long long sum = 0;
	while (r > 0) {
		sum += BIT[r];
		r -= (r & -r);
	}
	return sum;
}

long long inversion_number(int N, int A[], int B[])
{
	int i, a[100001], BIT[100001] = {};
	long long inv = 0;
	for (i = 1; i <= N; i++) a[A[i]] = i;
	for (i = N; i >= 1; i--) {
		inv += sum_BIT(BIT, a[B[i]]);
		add_BIT(N, BIT, a[B[i]], 1);
	}
	return inv;
}

int main()
{
	int i, N, P[3001], Q[3001];
	scanf("%d", &N);
	for (i = 1; i <= N; i++) scanf("%d", &(P[i]));
	for (i = 1; i <= N; i++) Q[i] = i;
	printf("%lld\n", inversion_number(N, P, Q));
	fflush(stdout);
	return 0;
}