#include <iostream>
#include <cstdio>


using namespace std;

const int maxlen = 100010;
long long res = 0;


int merge_sort(int *nums, int l, int r)
{
    if(l>=r)    return 0;
    int mid = l+r>>1;
    merge_sort(nums, l, mid);    merge_sort(nums, mid+1, r);
    int k = 0, i=l, j=mid+1;
    int tmp[maxlen];
    while(i<=mid && j<=r)
    {
        if(nums[i]<=nums[j])    tmp[k++] = nums[i++];
        else 
        {
            res += mid-i+1;
            tmp[k++] = nums[j++];
        }
    }
    while(i<=mid)   tmp[k++] = nums[i++];
    while(j<=r)      tmp[k++] = nums[j++];
    for(i=l,j=0; i<=r; i++, j++)   nums[i] = tmp[j];
}

int main()
{
    int arr[maxlen];
    int len;
    cin>>len;
    for(int i=0; i<len; i++)     cin>>arr[i];
    merge_sort(arr, 0, len-1);
    //for(int i=0; i<len; i++)     cout<<arr[i]<<" ";
    cout<<res;

    return 0;
}