#include <stdio.h>

#define N 262144
#define HALFN 131072 // 2^17
#define INFTY 1000000001 // 10^9 + 1

int cnt = 0, L[HALFN] = {0}, R[HALFN] = {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;

  // count the number of inversions
  for (j = 0; j < n2; j++) {
    for (i = 0; i < n1; i++) {
      if (R[j] < L[i]) {
	cnt += (n1 - i);
	break;
      }
    }
  }
  
  // sort array
  for (i = 0, j = 0, k = left; k < right; k++) {
    if (L[i] <= R[j]) {
      A[k] = L[i];
      i++;
    }
    else {
      A[k] = R[j];
      j++;
    }
  }
}

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("%d\n", cnt);
  return 0;
}