#include<stdio.h>

#define MAX 200000
#define SENTINEL 2000000000
long merge(int A[],int n,int left,int mid,int right);
long mergeSort(int A[],int n,int left,int right);

int L[MAX/2+2],R[MAX/2+2];


int main(void){
  int A[MAX],n,i;
  scanf("%d",&n);
  for(i=0;i<n;i++){
    scanf("%d",&A[i]);
  }

  long int a = mergeSort(A,n,0,n);

  // for(i=0;i<n-1;i++){
  //   printf("%d ",A[i]);
  // }
  // printf("%d\n",A[n-1]);

  printf("%ld\n",a);
  return 0;
}




long int merge(int A[],int n,int left,int mid,int right){
  int n1=mid-left;
  int n2=right-mid;
  long int count=0;
  int i,j,k;

  for(i=0;i<n1;i++){
    L[i]=A[left+i];
  }
  for(i=0;i<n2;i++){
    R[i]=A[mid+i];
  }
  L[n1]=R[n2]=SENTINEL;
  i=0,j=0;

  for(k=left;k<right;k++){
    // count++;
    if(L[i]<=R[j]){

      A[k]=L[i++];
    }
    else{
      A[k]=R[j++];
      count+=n1-i;
    }
  }
  return count;
}

long int mergeSort(int A[],int n,int left,int right){
  int mid;
  long int v1,v2,v3;
  if(left+1<right){
    mid = (left+right)/2;
    v1=mergeSort(A,n,left,mid);
    v2=mergeSort(A,n,mid,right);
    v3=merge(A,n,left,mid,right);
    return v1+v2+v3;
  }else return 0;
}

