#include <bits/stdc++.h>
using namespace std;

//macro-----------------------------------------------------------------------------------------
#define rep(i,a,b) for(int i=a;i<b;i++)
#define int long long

void print(int n){ cout << n << endl; }
int input() {int t; cin >> t; return t;}
//main------------------------------------------------------------------------------------------

struct fenwick{
    vector<int> bit;
    int s;

    fenwick(int n){
        s = n;
        rep(i,0,n+1) bit.push_back(0);
    }

    int sum(int i){
        if(i < 1) return 0;
        return bit[i] + sum(i - (i & -i));
    }

    int add(int i, int x){
        if(i > s) return 0; 
        bit[i] += x;
        add(i +(i & -i), x);
    }


};

signed main(){
    
    fenwick bit = fenwick(100001);

    int n; cin >> n;
    vector<int> arr; rep(i,0,n) arr.push_back(input());

    int ans = 0;
    rep(i,0,n){
        ans += i - bit.sum(arr[i]);
        bit.add(arr[i], 1);
    }

    print(ans);


    
  
    



}