#include<stdio.h>
#define I 200000000

long long int S[100000000];
int L[1000000],R[1000000];
int cnv=0; 
 
void merge(int *A,int left,int mid,int right){
  int i,j,k;
  int 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]=I;
  R[n2]=I;
 
  i=0;
  j=0;
 
  for(k=left;k<right;k++){
    if(L[i]<=R[j]){
      A[k]=L[i];
      i=i+1;
    }else{
      A[k]=R[j];
      j=j+1;
      cnv+=n1-i;
    }
  }
}


void mergeSort(int *A,int left, int right){
  int mid;
  int v1,v2,v3;
 
  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;
  int n;
   
  scanf("%lld",&n);
  for(i=0;i<n;i++){
    scanf("%d",&S[i]);
  }
 
  mergeSort(S,0,n);
 
  printf("%d\n",cnv);
  return 0;
}
 
 