/*
 *	argorithms and data structures
 *	lectuire 5 
 *	The Number of Inversions
 */
#include <stdio.h>
#include <limits.h>

#define INFTY INT_MAX
#define N 200000

int count = 0;

void merge(int A[], int left, int mid, int right){
	int i, j, k;
	int L[N], R[N];
	int L_elements = mid - left;
	int R_elements = right - mid;

	for(i=0; i<L_elements; i++)
		L[i] = A[left + i];
	L[i] = INFTY;

	for(i=0; i<R_elements; i++)
		R[i] = A[mid + i];
	R[i] = INFTY;


	i = j = k = 0;
	for(k=left; k<right; k++){
		if( L[i] <= R[j] )
			A[k] = L[i++];
		else{
			A[k] = R[j++];
			if(L[i] < INFTY) count += L_elements - i;
		}
	}
}	

void mergeSort(int A[], int left, int right){
	int mid;
	if( left+1 < right ){
		mid = ( left + 1 + right) / 2;
		mergeSort(A, left, mid);
		mergeSort(A, mid, right);
		merge(A, left, mid, right);
	}
}

int main(void){
	int A[N], n, i;

	scanf("%d", &n);
	for(i=0; i<n; i++)
		scanf("%d", &A[i]);

	mergeSort(A, 0, n);

	printf("%d\n", count);

	return 0;
}