 #include<stdio.h>

#define MAX 200000
#define INF 2000000000
typedef long long LO;
int L[MAX/2+2],R[MAX/2+2];

LO merge(int A[],int n,int left,int mid,int right){
  int i,j,k;
  int n1=mid-left,n2=right-mid;
  LO cnt=0;
  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]=INF;
  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;
}

LO mergeSort(int A[],int n,int left,int right){
  int mid;
  LO k1,k2,k3;
  if(left<right-1){
    mid=(left+right)/2;
    k1=mergeSort(A,n,left,mid);
    k2=mergeSort(A,n,mid,right);
    k3=merge(A,n,left,mid,right);
    return k1+k2+k3;
  }else return 0;

}

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

  printf("%lld\n",mergeSort(A,n,0,n));

  return 0;
}