#include <stdio.h>

#define MAX 20000000
#define SENTINEL 2000000000

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

long long merge(int *A,int n,int left,int mid,int right){
  int i,j,k,n1,n2;
  long long count = 0;
  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] = SENTINEL; R[n2] = SENTINEL;
  i = 0; j = 0;
  for(k=left;k<right;k++){
    if(L[i] <= R[j]) { A[k] = L[i++]; }
    else{
      A[k] = R[j++];
      count += n1-i;
    }
  }
  return count;
}
long long mergeSort(int *A,int n,int left,int right){
  int mid;
  long long 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;
}

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

  return 0;
}