#include <stdio.h>
 
#define INFTY 1000000001
#define MAX 200000
 
void merge(int *, int, int, int);
void mergeSort(int *, int, int);
 
long cnt=0;
 
int main(void)
{
    int i, n, A[MAX];
     
    scanf("%d",&n);
    for (i=0; i<n; i++) {
        scanf("%d",&A[i]);
    }
     
    mergeSort(A, 0, n);
     
    printf("%ld\n",cnt);
     
    return 0;
}
 
void merge(int *A, int left, int mid, int right)
{
    int i, j, n1, n2, k;
    int L[MAX/2 +2], R[MAX/2 +2];
     
    n1 = mid - left;
    n2 = right - mid;
    for (i=0; i<n1; i++) {
        L[i] = A[left + i];
    }
    for (i=0; i<n2; i++) {
        R[i] = A[mid + i];
    }
    L[n1] = INFTY;
    R[n2] = INFTY;
     
    i = 0;
    j = 0;
    for (k=left; k<right; k++) {
        if( L[i] <= R[j] ) {
            A[k] = L[i];
            i++;
        } else {
            A[k] = R[j];
            j++;
            cnt += n1 - i;
        }
    }
}
 
void mergeSort(int *A, int left, int right)
{
    int mid;
    if( left + 1 < right ) {
        mid = ( left + right ) / 2;
        mergeSort(A, left, mid);
        mergeSort(A, mid, right);
        merge(A, left, mid, right);
    }
}
