#include<stdio.h>
#include<stdlib.h>

void merge(int*,int,int,int);
void mergeSort(int*,int,int);
int count=0;

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("%d\n",count);
  
  return 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);
  }
}
  
  