#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#define N 10000000000

void merge(int *,int,int,int);
void mergeSort(int *,int,int);

int S[1000000000], L[1000000],R[1000000];
long long int cnv=0;

int main(){
  int i,n;

  scanf("%d",&n);


  for(i=0;i<n;i++){
    scanf("%d",&S[i]);
  }

  mergeSort(S,0,n);

  printf("%lld\n",cnv);
  return 0;
}

void merge(int *A,int left,int mid,int right){

  int i,j,k,n,m;

  n=mid-left;
  m=right-mid;

  for(i=0;i<n;i++){  L[i]=A[left+i];  }
  for(i=0;i<m;i++){  R[i]=A[mid+i];  }
  i=j=0;
  L[n]=N;
  R[m]=N;

 

  for(k=left;k<right;k++){
    if(L[i]<=R[j]){
      A[k]=L[i];
      i=i+1;
    }
    else{
      A[k]=R[j];
      j+=1;
      cnv+=n-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);
  }
}

