#include<stdio.h>

long long count = 0;


void merge(int A[],int left,int mid,int right) 
{
  int i,j=0,k;
  int n1 = mid-left, n2 = right - mid; 
  int L[n1+1],R[n2+1];
   
  for(i = 0;i < n1;i ++){
    
    L[i] = A[left+i];
  }
  
  for(i = 0;i < n2;i ++){
    R[i] = A[mid+i];
  }
  
  L[n1] = (1e+9)+1;
  R[n2] = (1e+9)+1;

  i = 0;
  
  for(k = left;k < right;k ++)
    {
      if(L[i]<=R[j]){
	A[k] = L[i ++];
      }else {
	A[k] = R[j ++];
	count += 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);
  }
}
 
int main() 
{
  int i,n,S[200000];
  
  scanf("%d",&n);
  
  for(i = 0;i < n;i ++) 
    {
      scanf("%d",&S[i]);
    }
  
  mergeSort(S,0,n);
  
  printf("%ld\n",count);
   
  return 0;
}
 