import java.io.BufferedInputStream;
import java.util.Scanner;
import java.util.Stack;

public class Main {
	public static int n;
	public static int[] x;
	public static int[] y;
	public static long result = 0;
	public static void msort(int left, int right) {
		int mid = (left + right) / 2;
		if(left == right) {
			return;
		}
		else {
			msort(left, mid);
			msort(mid+1, right);
		}
		int i = left;
		int j = mid + 1;
		int yy = left;
		while(i <= mid && j <= right) {
			if(x[i] > x[j]) {
				result += mid - i + 1;
				y[yy] = x[j];
				yy++;
				j++;
			}
			else {
				y[yy] = x[i];
				yy++;
				i++;
			}
		}
		while(i <= mid) {
			y[yy] = x[i];
			yy++;
			i++;
		}
		while(j <= right) {
			y[yy] = x[j];
			yy++;
			j++;
		}
		for(int ii = left; ii <= right; ii++) {
			x[ii] = y[ii];
		}
		return;
	}
	public static void main(String args[]) {
		Scanner in = new Scanner(new BufferedInputStream(System.in));
		n = in.nextInt();
		x = new int[n+1];
		y = new int[n+1];
		for(int i = 1; i <= n; i++) {
			x[i] = in.nextInt();
		}
		msort(1, n);
		System.out.println(result);
		in.close();
	}
}

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