import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] a = new int[n];
        for(int i=0;i<n;i++)
        a[i] = sc.nextInt();
        long res = mergesort(a,0,n-1);
        System.out.print(res);
    }
    private static long mergesort(int[] a,int left,int right){
        if(left>=right)
        return 0;
        int mid = (left+right)/2;
        long res = mergesort(a,left,mid)+mergesort(a,mid+1,right);
        int i = left,j = mid+1,k=0;
        int[] q = new int[right-left+1];
        while(i<=mid&&j<=right)
        {
            if(a[i]>a[j])
            {
                q[k++] = a[j++];
                res = res + mid-i+1;
            }
            else
            q[k++] = a[i++];
        }
        while(i<=mid)
        q[k++] = a[i++];
        while(j<=right)
        q[k++] = a[j++];
        for(int c = left,d = 0;c<=right;c++,d++)
        a[c] = q[d];
        return res;
    }
}