#include <stdio.h>

void mergeSort(int *, int, int);
void merge(int *, int, int, int);

long long count = 0;

int main(){
  int S[200000], n, i, j, temp;

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

  mergeSort(S, 0, n);

  printf("%lld\n", count);
  
  return 0;
}

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);
  }
}

void merge(int *A, int left, int mid, int right){
  int n1, n2, L[100001], R[100001], i, j, k;

  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] = 1000000001;
  R[n2] = 1000000001;
  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++;
      count += n1 - i;
    }
  }
}