#include<stdio.h>
#define MAX 500000
#define BIG 1000000000
int L[MAX/2+2],R[MAX/2+2];

long long merge(int A[], int n,int left, int mid, int right) {
  int n1 = mid - left;
  int n2 = right - mid;
int i = 0,j = 0,k=0;
long long 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] = BIG;
  R[n2] = BIG;
  i=0;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;
}

long long mergeSort(int A[],int n, int left,int right){
  long long v1, v2 , v3;
  if (left+1 < right) {
    int 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;
  scanf("%d",&n);
  for(i = 0;i<n;i++) scanf("%d\n", &A[i]);

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

  return 0;
 }