#include <stdio.h>
#define N 262144
#define HALFN 131072
#define INFTY 1000000001
int L[HALFN] = {0}, R[HALFN] = {0};
long cnt = 0;
 
void merge(int *A, int left, int mid, int right) {
  int i, j, k, n1, n2;  
  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;
  for (i = 0, j = 0, k = left; k < right; k++) {
    if (R[j] < L[i]) {
      cnt += (n1 - i);
      A[k] = R[j];
      j++;
    }
    else {
      A[k] = L[i];
      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);
  }
}
 
int main(void){
  int i, n, A[N] = {0};
  scanf("%d", &n);
  for (i = 0; i < n; i++){
    scanf("%d", &A[i]);
  }
  mergeSort(A, 0, n);
  printf("%ld\n", cnt);
  return 0;
}