use std::io::{read_to_string, stdin};

fn invcnt(arr: &mut Vec<usize>, lo: usize, hi: usize) -> usize {
    let delta = hi - lo;
    if delta == 0 {
        return 0;
    } else if delta == 1 {
        return 0;
    } else if delta == 2 {
        if arr[lo] > arr[lo + 1] {
            let temp = arr[lo + 1];
            arr[lo + 1] = arr[lo];
            arr[lo] = temp;
            return 1;
        } else {
            return 0;
        }
    } else {
        let mut res = 0;
        let mut left = lo;
        let mut right = (lo + hi) / 2;
        let left_end = right;
        let right_end = hi;
        let mut v = vec![];
        res += invcnt(arr, left, left_end);
        res += invcnt(arr, right, right_end);
        while left < left_end && right < right_end {
            if arr[left] > arr[right] {
                v.push(arr[right]);
                res += left_end - left;
                right += 1;
            } else {
                v.push(arr[left]);
                left += 1;
            }
        }
        while left < left_end {
            v.push(arr[left]);
            left += 1;
        }
        while right < right_end {
            v.push(arr[right]);
            right += 1;
        }
        for (i, &e) in v.iter().enumerate() {
            arr[lo + i] = e;
        }
        return res;
    }
}

fn main() {
    let temp = read_to_string(stdin()).unwrap();
    let mut iter = temp
        .split_ascii_whitespace()
        .map(|x| x.parse::<usize>().unwrap());
    let n = iter.next().unwrap();
    let mut arr = (0..n).map(|_| iter.next().unwrap()).collect::<Vec<_>>();

    let res = invcnt(&mut arr, 0, n);
    println!("{}", res);
}