#include <stdio.h>
#include <stdlib.h>
#define MAX 1000000001
int n,Left[100001],Right[100001],i,j,k,count=0,*A;
void Merge(int left,int mid,int right){
  int n1=mid-left,n2=right-mid;
  for(i=0;i<n1;i++)
    Left[i]=A[left+i];
  for(i=0;i<n2;i++)
    Right[i]=A[mid+i];
  Left[n1]=MAX;
  Right[n2]=MAX;

  for(i=0,j=0,k=left;k<right;k++){
    if(Left[i]<=Right[j])
      A[k]=Left[i++];
    else{
      A[k]=Right[j++];
      count+=n1-i;
    }
  }
}
void MergeSort(int left,int right){
  int mid;
  if(right-left>1){
    mid=(left+right)/2;
    MergeSort(left,mid);
    MergeSort(mid,right);
    Merge(left,mid,right);
  }
}
int main(void){
  scanf("%d",&n);
  A=(int *)malloc(sizeof(int)*n);
  for(i=0;i<n;i++)
    scanf("%d",&A[i]);
  MergeSort(0,n);
  printf("%d\n",count);
  return 0;
}
