#include <stdio.h>

/* Macro Definition */
#define MAX 200000

/* Prototype Declaration */
void merge(int *, int, int, int);
void mergeSort(int *,int, int);

/* Grobal Variable */
int S[MAX], L[(MAX/2) + 1], R[(MAX/2) + 1], n;
long long count = 0;

int main() {
  int i;

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

  mergeSort(S, 0, n);

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

  return 0;
}

void merge(int *S, int left, int mid, int right) {
  int i, j = 0, k, n1, n2;
  n1 = mid - left;
  n2 = right - mid;

  for ( i = 0; i < n1; i++ ) L[i] = S[i+left];
  for ( i = 0; i < n2; i++ ) R[i] = S[i+mid];

  L[n1] = 1000000500;
  R[n2] = 1000000500;

  i = 0;

  for ( k = left; k < right; k++ ) {
    if ( L[i] <= R[j] ) {
      S[k] = L[i];
      i++;
    }else {
      count += (n1 - i);
      S[k] = R[j];
      j++;
    }
  }


}

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

}