#include <stdio.h>
#define INF 1000000001
void merge(int A[],int,int,int);
void mergeSort(int A[],int,int);
long long count = 0;
int main(int argc, char const *argv[]) {
  int i;
  int num;
  int S[num];
  scanf("%d",&num);
  for( i = 0 ; i < num ; i++ ){
    scanf("%d",&S[i]);
  }
  mergeSort(S,0,num);
  printf("%lld\n",count);
  return 0;
}
void merge(int A[], int left, int mid, int right){
 
  int n1,n2;
  int i,j,k;
 
  n1 = mid - left;
  n2 = right - mid;
  int L[n1+1],R[n2+1];
 
  for( i = 0 ; i < n1 ; i++ ){
    L[i] = A[left+i];
  }
 
  for( i = 0 ; i < n2 ; i++ ){
 
    R[i] = A[mid+i];
  }
 
  L[n1] = INF;
  R[n2] = INF;
 
  i = 0;
  j = 0;
 
  for( k = left ; k < right ; k++ ){
 
    if( L[i] <= R[j] ){
      A[k] = L[i];
      i++;
    }
    else{
      count += (n1-i);
      A[k] = R[j];
      j++;
    }
  }
}
 
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);
  }
}