#include <stdio.h>
#define MAX 200000
#define SENTINEL 2000000000
typedef long long llong;

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

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

int main(){
  int A[MAX],n,i;

  scanf("%d",&n);

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

  llong ans=mergeSort(A,n,0,n);

  printf("%lld\n",ans);

  return 0;
}

llong merge(int *A,int n,int left,int mid,int right){
  int i,j,k;
  llong cnt=0;
  int n1=mid-left;
  int 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]=R[n2]=SENTINEL;
  i=j=0;

  for(k=left;k<right;k++){
    if(L[i]<=R[j]) A[k]=L[i++];
    else{
      A[k]=R[j++];
      cnt+=n1-i;
    }
  }

  return cnt;
}

llong mergeSort(int *A,int n,int left,int right){
  int mid;
  llong 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;
}
